I have the same problem, crashes on the same date. Its an ironman game if it matters. And uses 5 mods, but all are ok with 1.4. I can upload a save if u want.
And it happens in already various games. Playing north in 1º bookmark, Baelish on a Dance of Dragons, North with Robb in Clash of kings. With the only ones that do not happen to me is with the Targaryens.