Although I would have expected it to have fully loaded, but just not have any of the "Facebook Instant Game" API calls available.
Having scaling viewport fun now.
Change one setting, export, upload, run in messenger, look for result - repeat. For hours. And. Hours.
Same here, my game is scaling nicely on the desktop, in a responsive viewport of dev console and in the mobile Chrome -- namely everywhere, except on Messenger. Seems like Messenger just ignores my scaling settings completely.
How is your progress?