I got this as well over a variey of different terrain types. Just all of a sudden tectical battles run very badly from one point onwards, hadn't bout or used any new units either, seemed to be out of the blue.
It would be nice if the traversible mountainside tiles had an alpine ground type with conifers and/or scree on them. Tundra and Solid ice are a given. I'd also like some sparing 'blasted' crystalline ground to be added like the tiles around chasms with a Giant's Causeway effect would be nice. Also as mentioned above, true ruined cities that cover more than one tile would be nice. They don't have to give any resources extra just as mentioned above it