Masking data is bloating the auto-save folder to over 1TB.

I used the automatic masking tool to mask out roughly two hours worth of footage. Over the course of working on my project for approximately 12 hours, this has led to my auto-save folder to bloat to over 1TB. I thought it was safe to delete old masking data from previous auto-saves, but then my project crashed and set me back 3 hours. When I tried to open an auto-saved project file, it was asking for mask data from a few days prior that I had already deleted. So it seems like the latest auto-saved mask data was not sufficient to open the latest auto-saved project file, which makes zero sense to me. 
 

Can anyone help? I’m trying to either cut down on the amount of mask data or find which files are safe to delete, but I’d like to keep auto-save on for project files because Premiere is prone to crashing.