holding the space bar acts like hitting the last item you clicked on with the mouse, in this case the runway.
used to be where if you clicked on the icon on the clipboard to show ALT for example, while hitting space to brake while landing you'd toggle the base alts continuisally.
or like logging in, hit the space 3 times in AH 1 and you were in the MA, without a single mouse click.
my guess is it has manifested itself in a new way in AHII.