I need to make one change to a single user's VDI to enable thumbnail image previews in Windows explorer. This was something I had disabled using the OS Optimization Tool, but now I can't figure out how to get this setting reversed. The only "undo" I see is to undo all the settings. I've changed all the settings in the registry and GPO that I could find related to this to no effect. It's even missing the option in explorer. It's supposed to have this menu option:

But the VDI (same image but post-optimization) looks like this:

Any ideas?