Windows has two sorts of fonts. user-local fonts and system-wide fonts. Dunno how long it has been that way but it at least stretches back to winNT, so it's not a win10 oddity. I don't know how the underlying libraries work, either for windows itself or for fontspec. BUT... the solution to my "newbie" problem that I posted about a few days ago [as you can probably already guess] is that the fonts that I can't get LaTeX to use are fonts that [somehow] got installed as user-local. I'm in the process of reinstalling them system-wide and I fully expect it will all work perfectly.
Not a very serious bug [since for most people it is a non-issue], but I'd call it a bug in fontspec that it can't find user-local fonts.
Fonts & Character Sets ⇒ Limitation on fontspec for Windows
- Ijon Tichy
- Posts: 640
- Joined: Mon Dec 24, 2018 10:12 am
Limitation on fontspec for Windows
If you think that it is a bug, you should report it as a bug. Posting it in a LaTeX forum that is not the bug report forum of the package is useless.
Sorry, but I can no longer participate here as the administrator is trampling on my wishes on one of his other platforms. 
