As you can see from the screenshot some music downloaded, some doesnt.
This is not a new issue, I've had this problem in the past.
The suggestions the help team gave was to uninstall the app and re download all my music, which I did.
When this current problem reared its head again, I cleared all data, uninstall, re-installed, and some of the music downloaded, others not.
I adjusted the Deezer allocated space to 40Gb, which is almost 2.5x more than the data/space needed, according to Deezer data.
Furthermore, Ive read here that if it doesnt auto download, I have to use the manual selection.
Which does not exist.