Whenever I reach Wave 15, I can never skip the wave to continue back to Wave 1 for some reason. I also find that when loading into a save at Wave 15, the item shop doesn't open. 3 of my save files which were played on the previous version of the game don't even let me enter the rabbit hole now, so those 3 save files are essentially locked now since I can't fight the rabbits, nor go back to Wave 1.
Other than that, I love the spell system and the new scenes are noice too.