Not sure what happened but I was stuck outside boss battle with no button to get back in
#stuck on same stage
waxen axle
daring flare
You can try to clear your cache and app data, and reopening the game. If that doesn’t work, you can try to reinstall the game
flint violet
The exact same thing happened to me after i got a connection error while I prestiged.
What worked for me was that I force closed the game, and it worked when I started it back up again.
So hope that works for you too.