BUG: Summoned entities become unresponsive after a loading a game

PC, latest 2.1

Do you have any mods?
I have Call of the Wild, whose creator said this was a known 2.x vanilla bug.

Please explain the issue is in as much detail as possible:
If I summon some monsters, save and then load, some of them will become unresponsive (will just stand there, won’t fight or follow). Each time I load it happens to even more of them.

Does anyone know of this bug or know any workaround? It’s pretty impactful - my class is kind ruined.
Just tested it w/o mods and it still happens.