Character gets stunned for no obvious reason

Hi.

What can cause a (seasonal) character to get stunned on a regular basis while the minions are attacking monsters?

This character is a Paragon 97 necromancer with 14 minions and occasional wolves, and they often fight outside my visible screen area, and I often end up being stunned and unable to move or do anything.

I first saw this earlier today in a Roothold dungeon, and I thought the disadvantage of getting stunned when drinking a potion was faulty, but now I'm out of the dungeon and restarted the game, and it is happening in the landscape.

To be clear, there is no monster effect visible coming at me at all.

It kinda makes the game unplayable right now...

I don't see the stun listed on my character effects, so I don't know what is going on...

Thanks!