On the planet Quethold stormtroopers/phalanx troopers will spawn in as snowtroopers.
Selling the pathfinder of your fleet in orbit when invading a planet will show what ground units the enemy has.
The MMT attempts to crush infantry but doesn't actually crush them.
Greater Maldrood will invade my planet, garrison a bunker, then use its bombing runs/bombardments solely to kill anything I send at the bunker. (I don't know if this is for Kessel specifically)
On Bilbringi Airstraekers will execute a weird string of patrolling where they'll guard various props/bunkers, refusing to attack my units within line of sight.
*I don't know if all of these qualify as bugs, but I thought it would be helpful.*