I had one other player report something like this a week or two ago (on an earlier version) . And then it seemingly fixed itself and then would only occur in one boss fight later. If you haven't already, can you send me an email with your save attached? I would like to look at it Monday to try to understand why this happens randomly. Also: try using Leech or File Extraction if you have those programs and see if enemies start animating again.
I'm also getting this exact error you mentioned. Every now and then, I just straight up cannot see the enemies unless I use Leech or File Extraction. Not unplayable, but definitely awkward. I'm on Windows 10, playing version 1.5.7. I can send over a save if that'll help.
That's the only bug I've run into. The game is fantastic so far!
Edit: Went ahead and sent an e-mail. Hoping it's an easy fix for ya.