Hmm, that's definitely an issue - looks to me like a form of recursion gone bad when a unit group finishes forming/starts to move to attack.
By chance, how do you have your settings configured? That is, startup and runtime?
I've experienced this locally when I was developing the unit group cloning, but have not experienced it since fixing the logic; that said, that logic has not been tested with other mods that may create their own unit groups - so my guess is that there is some interaction going south as a result.
If you can at all narrow down what might be triggering it/which mod interaction, that would be supremely helpful; but no worries if not.
In the meantime, I will try and see what additional logic/safeguards I can add to hopefully prevent this kind of an issue.
Also, few last questions if you don't mind: how frequently does this occur? And is it intermittent, or consistent?