Help! Every save on my External Hard Drive is unable to be loaded!

Hi there,

I have multiple saves on my External Hard Drive (F) because my local SSD (C) is too full. I save weekly in-game with a 5-save rolling. Yet, today when launching the game I cannot load any saves from my F drive, even saves from months ago. I have tried moving the saves to a different location (D) and I've had no success. What's going wrong here? I take it there's something up with my drive, but it's plugged in and seems to be working otherwise. What steps can I take to get my saves back?

Thanks.