Hmmm. I got that error in the old build, which had Yanfly's Battle Engine Core enabled on, but once I took it off, it was fine.
The only thing I can think of is make sure you're deleting the old game version(s), and if you have yanfly's battle engine core on/installed, turn it off.
The only thing those creatures can do is the basic attack, which EVERYONE including the Player characters do.
I wish I had another PC to test it on. I'll put up a post asking if others are having trouble with this particular issue.
I've attached the problem file, which you can download and input into your game manually if none of the above works: https://fury-glitch.itch.io/sex-almighty/devlog/197991/is-anyone-still-having-is...