I’ve looked around and can’t find anyone else with a similar issue, so I’ll post it here.
I was banging my head against the wall trying to figure out why I suddenly couldn’t access my files and I think I figured it out.
Raspberry Pi 2, video library is stored on my PC, accessed through Windows SMB. My PC is running Windows 10, and after it automatically installed and updated the July patch, I could no longer access my library. Internet was working fine, but I was locked out of my files. Once I rolled back that update, everything returned to normal. Last night Windows automatically downloaded the same update and I encountered the same issue.
If anyone else has a similar issue, the updates that were problematic were KB4033637 and KB4025339.