Can't enter waypoint lat long if harrier spawns without waypoints?

I'm spawning into a harrier with no waypoints set. It seems I can't get the aircraft to accept a new one.

Whenever I enter the N and E and press enter, the numbers don't show up on the MFD. This is where things diverge from the instruction videos on youtube and that's as far as I've gotten.

Press the Mk0 button, and then you can add waypoints. It's a very long-standing bug.

I thought I remembered something about a waypoint bug...

Thank you, that worked.