I appreciate the efforts of @awesomemac and hope they will lead to positive results. I have done some additional tests myself, and here are the steps I followed:

1. I have turned off the "Synchronized Queue-list" feature on all my devices.
2. I haven't used the "Shuffle my music" feature for a few days, either on the Web Browser of my notebook or through the Android App on my phone.
3. I started the "Shuffle my music" feature using the Web Browser on my notebook, and it worked perfectly. It added 50 songs to my listening queue, selected from all my favorite tracks, albums, and playlists, without repeating any songs between different sets of fifty. In fact, it should have a thousands options of mine to shuffle, and I had not listened to most of them in the past month, making it a very enjoyable experience.
4. However, when I turned on the "Synchronized Queue-list" feature, the "Shuffle my music" function in the Web Browser on my notebook began to malfunction again. It added only about ten or twenty songs at most, always from the same small group of artists, resulting in frequent and likely repetitions. I have seen these songs numerous times since the issue began a month ago, and they keep coming as if I had only a few dozen or hundreds of songs available for selection. Additionally, it seemed to focus exclusively on the same genre, which is quite unusual.
5. After disabling the "Synchronized Queue-list" again, logging off, and waiting about half an hour before logging back into Deezer, the "Shuffle my music" feature in the Web Browser on my notebook has returned to normal operation, as described in point 3.
6. The "Shuffle my music" feature in the Android App on my phone has consistently performed poorly, as I mentioned in point 4, both when turning on and off the "Synchronized Queue-list".

@YannickG and @geo79, maybe you could try this as well to see if you experience the same issue I did by following my steps, or if it continues to add songs unrelated to your favorite tracks, albums, and playlists.

In any case, the problem has unfortunately not been resolved yet.

I’ve turned off Synchronize on all three instances where I use Deezer (Android app, Windows app, web browser) and started new Shuffles on all three: 

• Windows app and web browser both gave me short Shuffle queues (11 tracks and 17 tracks respectively).  All songs were from my favorites, but as before, it’s mainly picking from the same dozen or so artists.  Both queues had a lot of artist overlap, even though my library has almost 400 artist favorites.
• Tried a second time on the Windows app and it made a Shuffle entirely of stuff NOT in my favorites, and not related at all to genres that I listen to.
• On the Android app I tried three times.  First it gave me a Shuffle with 15 songs all from my favorites, but again only picking from the same dozen or so artists as on the Windows app and web browser. 
• Second try on the Android app gave me a Shuffle with 14 songs, 2 of which were from my favorites, and the rest were NOT in my favorite artists, tracks or albums.  But those other 12 were at least in similar genres to what I listen to.
• Third try on the Android app - 13 tracks, and only 1 from my favorites.
• It’s like the more Shuffle is used, the worse it gets.

shuffle my music is my favorite feature!

New Update: I listened to my monthly top smart playlist with the Android App on my phone. After that, the "Shuffle my music" feature in the Web Browser on my notebook started working very poorly again. It only added about ten songs to the queue, always from the same limited group of artists... in short, the usual issues I have been reporting for a month now. However, after waiting a few hours without using Deezer at all, it fixed itself.

To summarize: "Shuffle my music" is still unusable from the App but works properly from the Web Browser. However, if I use the App, it negatively affects the Web Browser version as well, even though the "Synchronized Queue-list" feature is disabled. I also find that after listening to content through the App, I must wait several hours before I can enjoy the "Shuffle my music" feature working correctly again in the Web Browser and adding 50 songs to my listening queue from all my favorite tracks, albums, and playlists with almost none or very few repetitions between different sets of fifty songs.

Thank you @Marcormark for your update.

As long as I do not use the Android App or wait a few hours after using it, there seem to be no more issues with the Web Browser on my notebook. I am still experimenting, though. For example, I tried Flow and noticed the genre, favorite artists, and even almost all of my favorite songs included in Flow were exactly the same as those in the "Shuffle my music" feature when it malfunctions.

The interference between Flow and the "Shuffle my music" feature, as well as between the Android App on my phone and the "Shuffle my music" feature in the Web Browser on my notebook, is quite peculiar. I hope my tests can help Deezer team reproduce the problem and understand what has been happening for over a month now.

@Marcormark Sounds like Deezer should give you some free months for all this bug testing since you’re literally doing their job for them. Thank you for your efforts!

For me, the web browser version is still stuck giving me a short, repetitive Shuffle with the same dozen artists every time.  And it’s frequently the same songs that keep showing up in every single Shuffle too.

A short update.  I logged out on all my devices, waited a bit, logged in only on web browser, and it actually gave me a 48 track Shuffle that pulled from my whole library of almost 400 artists, instead of the dozen it was previously stuck with.  Will try on other devices later.

Yes! I am very happy my workaround is effective for you as well and somehow restores the "Shuffle my music" functionality as it should at least in the Web Browser version!
Unfortunately, there is still no hope for the Android App.

Give a try to spotify to get satisfactory functionality,

Yes! I’m glad the workaround is restoring the 'Shuffle my music' feature in the Web Browser version. Sadly, no luck for the Android App yet. 

By the way, for video editing, you can try tInShot Editor](https://inshoteditor.com) – it's really handy!

Shuffle is still not working properly.  No official solutions from Deezer after a month. 

My shuffle is working. And with favourites I like or would like, but the shuffle playlist is just 23 songs.

Mine still keeps adding music that is not in my favorites on all three instances - Android app, desktop app and web browser.  The only way to get it to behave temporarily is to clear caches, log out on all and then ONLY use the web browser version.  But eventually it starts acting up again.  This means I can’t use Shuffle while driving, and that sucks.

They finally got back to me yesterday. They should update the algorithm next week to reduce repetitions and remove those glitches that introduce traces from outside the library.
Fingers crossed! 

That’s good news.  Thanks for sharing.

I tried the "Shuffle my music" feature both on the Android App and on the Web Browser version, and it seems they have finally fixed it! There are no longer tracks outside of my library; even turning the "Synchronized Queue-list" feature on again, it keeps selecting songs from my favorite tracks, albums, and playlists. There may still be just a few too many repetitions here and there, I would say among the songs I have listened to the most or that I have preferred recently, but it is no longer so annoying and works much better than it did in the last three months.

I recently noticed that when I use the 'Shuffle my music' feature on Deezer, it also plays songs that I don’t even have in my favourites or in any playlist. That really annoys me.

It seems to be working once again for me as well.  Tested on Android app and Windows desktop app.  Decent length shuffles with little to no repetitions.  Seems to be pulling from my entire library of favorites.  And as an added bonus, they finally fixed the broken Favorites tab in the desktop app which had been broken for me ever since the rebranding!

Try clearing your caches and logging out on any devices that you use for Deezer.  Wait a bit, then log back in and try your Shuffle again.  Seems like they’ve fixed it but clearing out the old cache might be an important step.

I really don't know how it is possible that they may have solved the problem for some of us only to see it start affecting other users. 
Hopefully clearing the cache helps.

Hi, thank you for your comment to my question on the other thread and for your workaround here.

First of all, following Leonídia.Deezer advice (thank you for that) I turned off the “automatic recommendations” which I was not aware of and so stopped listening to music that was not in my library. This feature in fact is something like a much better Flow feature when you turn it on, as you can listen to your library (not only artists and genres) and get a suggestion every now and then which is just great to me. 

But overall the performance of shuffle my music is quite random now, I have to say. Far from what it used to be. For a few weeks this feature was clearly the same as Flow, even “shuffling” the same songs out of a library of over 50.000 tracks.

Now I usually get a 50 track playlist to start with, and many times I get songs never played before. But I get the feeling that certain artists come up again and again and sometimes I even get the same song three times in a week. With my library and a proper shuffle feature I should not even listen to the same song twice in my whole life  Other times I only get a short list and it will even stop playing reporting an error once the last song ends. In android I usually get only 12 or 20 songs and the repetitive pattern is much more noticeable.

Hi, maybe you tried this, but just in case… It worked for me as I was not aware of this button in the new version. Switch off “automatic recommendations” next to the playlist header

@JRR I had the same experience, 20 songs when using Android. And 4 of those 20 songs are not from favourites I would ever listen to.

Sometimes I feel this way too, but it is a very slight and bearable flaw. If I notice that a song comes up too often for my liking, I just skip it, and it doesn't seem to me that this affects the quality of the shuffle, so I'm happy with it.

This was one of the many issues I reported in previous months, but in the last few weeks it seems to be fixed for me. I have no idea why it is different for you now...