After some further testing i think i sorta figured out what was going on here. (In my case at least)
It seems like some (or all?) changes to scripts are not properly loaded into existing GM Mode scenes.
The text worked fine in the editor but wouldn't show up in a GM mode scene that had been around for a while.
After creating a new scene in the same GM mode project, it worked as expected.
Maybe that's by design and i just missed the note on it, maybe not.
Problem solved either way