Just hit a bug where I can't select any enemies to attack :(
I'm experiencing the same in the new swamp. Very reproducible too, every time the front enemy dies to my spikes. Might just be from spikes, might be from any effect killing the front enemy outside of your turn, but after the game seems to be trying and failing to target the enemy at the front without moving on. guess be careful playing with spikes in the new area until it's fixed