Exception thrown. Crashes whilst loading a specific map in PIE and opening blueprints

I’ve got an issue I can’t seem to shift. Suddenly it seems that I can’t open a umap in PIE. The main menu opens fine, but when I attempt to go to the next level, I get:

It seems like some of the associated BPs also crash when I attempt to open them. I get this warning, but I’m not sure if it’s related:

I’m guessing that this is a corrupted BP of some sort but I’m not sure how. I play in the editor whilst I’m working, everything seems fine and then I check in and this stuff starts happening. Any ideas?