I'm having projects fail to load when using external drive

LOG: [Project management] Failed to open project 'F:/Models/Imperial Knight/PILOT_HELMS.spp'

I got a new SSD external drive and have been using it for about a week now, after moving all my substance related SPPs and work to it for convience between PCs.
After working on a project the SPP would save and could be opened again, however after the drive was removed the project was no longer opening with the same error above. I tried with 2 more models and replicated the issue to get the same error. But whats odd is the drive still consists some of my other work and can load up into substance fine but if its saved again then it becomes broken.
My cache is set up to link to my F external.
Projects are being saved directly from Substance on my C to my F external drive.
Other projects open fine but if saved again will get the error.
Other files are accessed with no issues to and from the drive.

A link to the SPP (zip) 
https://drive.google.com/file/d/11BwwCqykvPuVtZCMCvzADKGLmRwhF5jI/view?usp=sharing