I haven’t seen this bug mentioned anywhere else:
When two Abomination+ stand next to each other and of them is killed it will cause the second Abomination+ to disappear (it’s not killed because it doesn’t spawn anything)
This seems to only happen when the Abomination is killed in a corner. As can be seen in the pic the Abomination just behind the one getting killed simply disappears
The version I’m running is GOG v.1.0.52
I’ve also added a savegame if it’s necessary for a reconstruction of the bug, just place the defenders in NG+“Night of the living Knights” as seen in the picture and let it play a few times. I’ve tried it several times myself and whenever the killing shot hits the Abomination in a corner the bug appeared.