Once items become unupgradable, you shouldn't be able to 'upgrade' them in the shop. Wasted a lot of money trying to upgrade things that couldn't get better anymore.
@LoZio1 - there is a bug that removes all your equipment and spell cards sometimes. If it happens, run away immediately (you won't lose anything) and just equip everything again.
To beat levels you have to meet objectives as well as get enough points for at least one star, which is why it sometimes looks like you've beat the level when you haven't. Yeah, it's stupid.
thanks for trying the new levels! the starting point is the 5 heart, there's only one way to satisfy that clue