Why Do Some Fonts Only Appear To Load For Some Users And Not Others

I downloaded a truetype font from here: https://github.com/Templarian/MaterialDesign-Font/blob/master/MaterialDesignIconsDesktop.ttf

I tried installing it in /usr/local/share/fonts/MaterialDesignIconsDesktop/MaterialDesignIconsDesktop.ttf.

When I run fc-cache -fvr as root I see the file is detected:

root@localhost:/usr/local/share/fonts# fc-cache -fvr|grep MaterialDesignIconsDesktop
/usr/local/share/fonts/MaterialDesignIconsDesktop: caching, new cache contents: 1 fonts, 0 dirs
/usr/local/share/fonts/MaterialDesignIconsDesktop: skipping, looped directory detected

And I see the font is listed by fc-list as root:

root@localhost:/usr/local/share/fonts# fc-list|grep MaterialDesignIconsDesktop
/usr/local/share/fonts/MaterialDesignIconsDesktop/MaterialDesignIconsDesktop.ttf: Material Design Icons Desktop:style=Regular

However when I exit from my root login back into my normal account and run the same commands, the font is detected by fc-cache, but isn't picked up by fc-list:

 % fc-cache -fvr |grep 'MaterialDesignIconsDesktop'
Unable to revert mtime: /usr/local/share/fonts/MaterialDesignIconsDesktop
/usr/local/share/fonts/MaterialDesignIconsDesktop: caching, new cache contents: 1 fonts, 0 dirs
/usr/local/share/fonts/MaterialDesignIconsDesktop: skipping, looped directory detected
 % fc-list -v|grep MaterialDesignIconsDesktop
 %

I tried putting the TTF file in /usr/share/fonts/MaterialDesignIconsDesktop/ as well as ~/.local/share/fonts/MaterialDesignIconsDesktop/ with the same result.

I also made sure the font dir (a+rx) and file (a+r) are globally readable.

I have similar problems with a couple of other fonts, but this one is representative. I should add that there were some other fonts I installed without problem too - so it's not a blanket issue.

I'm running Ubuntu 22.10.

UPDATE

Seems to be something specific to my user (non-root) account. I created another non-root account on the same laptop, and when I login there, the font is being picked up just fine.

But I don't really want to migrate to a new account just for the sake of a font - especially if I end up simply reproducing the same problem once I finish the migration...

Ok so I went into Font Manager (font-manager) and noticed that the above font was listed but it was "unchecked". And as soon as I marked it "checked' the font appeared in the fc-list output.

I have no idea why I had to do that specifically for that font but not others. Perhaps I accidentally "unchecked" it previously when using Font Manager to browse the fonts.

In any case, this fixed the problem.