Sorry for resurrecting an old thread.

I came across this issue and thought i'd post the fix that worked. All text disappeared on some Wimdows 10 machines after copying some old group policies into the Win10 container. Turns out some of the policies had overwritten the permissions to multiple folders within C:, in particular it had removed "All Application packages" and "All Restricted App Packages" from the "c:\windows\fonts" folder.
We fixed it by using psexec from another machine, to run the command "ICACLS.exe c:\Windows\Fonts /T /Q /C /RESET" to reset the permissions (and then ran "ICACLS c:\Windows /T /Q /C /RESET" when we found some other permissions were affecting other apps).