You need to post in the Microsoft Powerpoint forums.
These are the Adobe forums.
Yes, BUT the fonts are Adobe Products. If there's an Adobe restriction, writing Microsoft will do me no good. AND, as I noted previously, I am indeed writing to BOTH forums.
[topic moved to Typography forum]
This is something that gets Windows users confused on a regular basis. There is nothing wrong with the fonts; what you're seeing is standard behavior for font menu lists on MS Office apps. Let me explain.
In many Windows applications, instead of every font appearing on the menu, fonts are grouped into style-linked sets, and only the name of the base style font of each set is shown in the menu. You can see this with the Times New Roman fonts, for example: there are 4 fonts installed — Regular, Italic, Bold, Bold Italic — but only the Regular, i.e. the base style, is displayed on the font menu. How does one get to the other styles? By pressing on the B and I buttons.
The Myriad Pro family works the same way; the Semibold fonts are style-linked with the Light fonts, and the Bold fonts are style-linked with the Regular (and Italic) fonts. So to get the Semibold, you first need to select the Light font on the menu, and then press on the B button. Similarly, to get the Bold font you first need to select the Regular font.