A bug about the battles related to the Prime Enchanter

(The video is sped up 2.5x) In the fight with the resurrected Prime Enchanter, I farmed the enchanter's gear by just returning to the checkpoint, but a bug happened during the fight. This enchanter wouldn't move and just kept repeating one move, and sometimes might even fall to their death. I'm not sure if this bug is because of refreshing by returning to the checkpoint.