Game crashes on the 18th of random months

I have a weird CTD issue: I get frequent CTDs, which always happen on the 18th of a given month. They are not set to any specific 18th though, if I load a game it generally will work for a bit and just end up crashing on a different 18th a couple months or years later. I started this save with the Century of Blood bookmark on Version 2.1, however I now updated the mod to 2.2 (deleted all the mod files) and CTDs are still happening. The issue has been around since i started the save but it has become much more frequent to the point of taking away a lot of the enjoyment. I uploaded the save file, if anyone wants to take a look at what might be causing this: