Today I finally figured out what broke System Restore / Volume Shadow Copy Service on my system - ASRock's XFast USB utility, of all things. I didn't figure it out myself, I saw it mentioned somewhere while I was banging my head against a wall trying to determine why nothing could create restore points* and thought, well I've tried everything else, let's see what uninstalling it does. Presto, it works again. The utility itself hasn't been updated for about 2 years, and Windows 8 and up don't enjoy any benefit from it (if it would even install, have no idea) since they natively support UASP**. It's a shame, as it does significantly boost file transfers over USB 3.0 in Windows 7.
*Not that I've ever successfully fixed anything using a restore point
**The Etron USB controllers that some ASRock boards used have broken streams support (would never come into play in Windows 7)... I'm not actually sure yet what happens when you try to transfer files using those boards and Windows 8/8.1/10. I do know that the native generic XHCI driver does not play well with the Etron controllers
