Units stuck when after they destroy the packed landmark of Mongols

Hey everyone, I was playing a team game with Rus against enemies where one of them was Mongols.

I was attacking a landmark which got packed, I followed it and destroyed the landmark when the packed landmark was not moving. I had like 5 horsemen attacking them and when they destroyed the landmark, the units got stuck in the landmark forever. I had to delete them.

I will soon attach a picture or video, give me some time and I will edit the post accordingly.