I've been having this issue since around 2017/2016 or so. I'm trying re-installing the app now. After installation I did not lose any tones I had saved.
I'll check back in a couple of days.
Edit (2021-07-22): I have tried to log out/uninstall/etc all the basic troubleshooting things, and I still have this issue every practice session. Explicitly, it will work after the troubleshooting but only until the next practice session.