It did happen once on Arcanus, but it seems much more frequent on Myrror; and I'm fairly sure it only, or nearly so, happens when the combat is at a settlement.
I tried again on a Bazzite laptop. Spent a while building Dwarf cities on Myrror; over hundreds of turns and regular attacks from raiders, no glitch. I conquer a neutral town, and 4-5 battles later, the glitch happens. The trigger seems to be conquering a neutral town on Myrror; I have not seen it otherwise. I'm not sure if it's the first town I conquer, or at random. I don't think it has anything to do with the race of the town; it's happened with towns of multiple different races. I don't know if it only happens if the town has defenders when I take it.
I think this is resolved now. The issue was that raider cities did not initialize the "producing unit" field correctly, so when you conquered a raider city, the city would immediately produce a unit with an uninitialized value, which showed up as a blank tile and immediately crashed the game if you interacted with it. The fix is to always initialize the "producing unit" field for every city.