Valid font displays only A & B

I just purchased a font collection that displays perfectly on the vendor's Mac, and in a glyph display on a site like FontDrop.info. However, when I double-click on either the otf or ttf file, or attempt to install it in Font Book, it displays only the characters A & B (it is an all uppercase font) and does not appear in any application font list. Also, behaves exactly the same on my two computers, an iMac and a MacBook Pro, both running Big Sur 11.4. The font passes validation.

I chatted with Apple Support and since all other fonts display correctly, and I can install other upper-case font with no problem, they don't think it is an OS issue.

I am at a complete loss. I'm still communicating with the vendor and the font creator. I really need this particular font to recreate a logo.

Hoping someone has some insight as to what could possibly be the issue and how to resolve it. :)