In the scene view pressing any of the shortcuts, e.g. 2 for top, does nothing. But, if I select "top viewport" from the viewport options menu, that works.

Am I missing some mode that I need to be in to use the keyboard shortcuts?

Hey kenned-doll,

you have to be in the camera state to make the shortcuts work. So while in the viewport press Esc to enter the camera state. Alternatively, you can hold the volatile camera state shortcut alt and then press 2.

Cheers
CYTE