In Warhammer 2 there was a bug where game wouldnt' find a map for specyfic situation up in Norsca and you would have "naval" battle with 99% of the battle map being water.
In IE i found simmilar bug.
Starting zone in the map was in lef upper corner (on a cliff). After starting the battle it took me a while to realise I can go down the cliff. Up on the cliff you can walk inside the building.
Funny part is, there is no enemy on the map, and the battle still goes on. There is no way to win.
The way I think it happened is that I ambushed Eltharion in ulthuan BUT there is like 100 slaanesh corruption so the game didn't find a map for this situation.
Or something else bugged out
Screenshots in link
https://imgur.com/a/meVOLg3