Mac menubar access with Control+F2

With VoiceOver enabled, there are two ways to move focus to the Menubar. Press VO+M, or press Control+F2. However, it seems that Control+F2 often stops working. Does anyone know of a setting that would enable or disable this keyboard shortcut?

Interestingly, when Control+F2 is non-functional, Control+F3 still works to move focus to the Dock. And, once focus is in the Dock, Control+F2 works again and moves focus to the Menubar. So it's very strange.

The workaround would be for me to just develop the necessary muscle memory to use VO+M, but I'm in the habit of using Control+F2 and can't seem to break it.

Thanks.