Stumped by Keyboard.AltKey

I’ve got a head-scratcher. In my app, during App.EnableMenuItems, Keyboard.AltKey and Keyboard.AsyncAltKey will not return true no matter what. Consequently, I can’t change the text of my menus before the user sees them.

But when I tried to make a small app that showed the “bug”, it worked perfectly. Anybody encounter something like this?

(The Mac version works perfectly, naturally.)