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.
Setup:
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.