yeah it was the chink in the pedestal!
having exhausted all other possible ways into that pit around the perimeter, i resorted to trying to jump upon/over the little walls along the steps to the blue key.
only after accidentally finding myself stood upon the pedestal did i study it closely and notice the chink. i wouldn’t have noticed it otherwise.
i wasn’t even sure if that was intentional or a ‘vertex snapping’ glitch that can happen in the editor, because i’d had a few of those when making my map.
