What does diskpart show?

If it were just file Explorer, I would say look at folder options View -> Hide Empty drives (just in case Windows thinks it's an empty drive). Since Disk Mgmnt also show the missing drives (or doesn't show in this case) - that's probably not it.

What's the status of the NVidia controller in Dev Mgr? Can you compare the driver version to 9926 or a previous TP?