I'd like to point to this reddit thread about Total War: Warhammer II which points out that units on battle maps stop on their own doing whatever they are ordered to do.
I don't know if the same happenes in multiplayer though I think the problem is there too at least from the little MP matches I saw through twitch streamers.
It's definitely there for singleplayer campaign which is super annoying.
Just to be sure,
- I don't know how to reproduce this issue I just know that many players complain about it.
- I don't have any mods.
- Latest version from Steam (I don't have beta patch option turned on so only stable release)
- When I notice it again I'll try to save the replay. I came to post about it later after I quit the game.