While I would like to figure out what exactly is causing the problem, I am able to fix it temporarily on Windows 7. The problem eventually returns however.
If you navigate to
C:\Users\(Your User ID)\AppData\Roaming\Adobe\Adobe Photoshop CC 2017\
Delete the CT Font Cache and Font Feature Cache folders. Photoshop will recreate those folders and files when you start it up, and you should be able to filter by classification for a while. I'm assuming you'd delete the same folders wherever they reside on a Mac or earlier version of Photoshop.
It would be nice to figure out why this keeps occurring though.