What you were expecting to happen, and what actually happened
Expected to be able to upgrade pet. Can’t.
How often does this happen? When did it begin happening?
Started happening when I got my fifth Tinycorn yesterday. Still can’t upgrade it.
Steps to make it happen again
Tap Troops → Pets → Tinycorn → Upgrade → Level Cap.
Tap uselessly and repeatedly on Max Level Ten. Look between where it says Cost x5 and You have x5 a few times to make sure I’m not crazy.