I cannot play past a specific date (25th of Obsidian, 71) in my 21 year fortress. It freezes consistently at the end of that date, I can still play the game just fine up until then. I've absolutely no clue what is causing the freeze, I thought it might be a forgotten beast fighting some demons, or some bugged construction blueprints after doing some googling, but everything I have tried to do differently doesn't fix the freeze.