Strange graphics bugs (relating to buttons), that I never figured out were the cause of similar crashes I was getting in my mod. Sometimes the button would be a blank box (not a pink box) and clicking on the unit, or the AI trying to build the unit caused a crash. This also happened with certain terrain types when I added some stuff from next war. I had to clone the data for the units, and terrain types and put all the defult stuff that was buggy in a way that made them unbuildable. For instance Currently in my mod, if you check the CivPedia the War elephant is still there (it's just called Broken War elephant) and only becomes available with oil and fusion (so it'll never be built). What's wierd is that the data the current war elephant uses is just a copy and paste of the original. So I have no idea what caused this, but that's how I fixed it. Not sure if this is a related bug, but it sure sounds like what was happening to me. Has anyone noticed any blank button boxes (not pink, just blank), in WB or City build screens--also this didn't happen all the time, maybe 1 out a 100 times for the war elephant, it's just that if 200 War elephants get built in a game, by me or the AI that makes it pretty probable the game will crash
What makes me think it's related is that most of the units I use in my mod are pulled from the Wolf mod, and up until recently my mod was just a skimpier clone of the Wolfenshanze mod (personally I think Wolf's mod has too many units, matter of taste), so I was curious why this never happened to the wolf mod.