@Leon Hermans I am sorry that you are experiencing problems with the app.
Can you please try the following steps one by one and test if it works after each step?

1. Restart the app (kill the app and remove it from the notification bar)
2. Try another network (4G or Wifi)
3. Restart your phone
4. Delete all the cache & data from the app (Data and storage, and then “Clear all”), then restart the app
5. Un-install the app and re-install the app

Please let me know if that works.