I’ve been having this problem with exp. at first only a couple monsters wouldnt get exp after a battle, now only one of then does, like in the picture i attached, none of the level 30s get exp. and wheneve i try leveling them up with potions, i love the potions but they don’t get any exp and the gold doesnt get spent.
I have the same problem a few of my units stop getting XP at 33.
Mine at 40
Monster exp cap at +20 levels i think. So if the monster is level 20 and your character is 40, it will receive no exp