AI unloaded from vehicles during combat will sometimes form their own rogue group.
In the spectator menu, another group with no units will appear on units list. The rogue AI is in that group based on it's overhead icon but in the units list the AI is still in original group.
The rogue AI will lose all waypoints of original group. This will result in stranded AI units just staying at the position. With multiple vehicle group, it results in multiple rogue groups and stranded unloaded AI.