On the app right now, I tried to get my messages to load, and it was stuck on the 'page loading' screen. Then I tried to load the study center, and it kicked me back to the dashboard. Tried to load the forums to post this error message, and it did the same thing. Trying to load a quiz directly from the dashboard leaves it hanging with the loading circle forever. Right now the only thing that seems to work is loading the other tabs of the dashboard (stats, hanko, etc).
Sounds like somehow it got a bad grab of the files. Try this for me - long press on the icon, go to app info, then Storage&Cache > clear storage. See if that changes it (will require a relogin)