TY. It worked. Didnt go back for enough.I went back to a save well before 12 and it loaded, and then played through perfectly. Neither a 12 nor 13 save worked.
We're consuming a game in ongoing development. As a software guy I can tell you backward compatibility is among the most difficult things to maintain. Looking into issues with another game i've realized that the initial startup where global variables are set is partially bypassed when you load a save. I understand my language is hedging a bit, but I'm a long way from understanding the details. Point is loading an early enough save lets the game set them as it goes along instead of expecting them to be there, or it just dies because the code has changed too much.
Take it as it comes.