"So much fun!" finally unlocked, after many times of clearing cache, trying a different browser, redoing it again, etc...
The in-game time was 1 hour, 32 minutes, and some seconds at the point when it finally decided to award me the medal which is supposed to award after only 1 hour.
Maybe since that time I didn't clear cache when it didn't reward, and had just reloaded again, the game finally noticed? Although I did play for a few minutes before it randomly awarded. Just putting it out there this might be a problem medal for people but if you reload the game (don't reset cache!) and keep playing it might award at some point.
And yes it did "award" with a 0 points medal at the 1 hour mark. But not the actual medal. So if the medal popup in-game says 0 and not 50, this is happening to you. Reload the game and keep playing on (but don't reset cache) and maybe it finally awards.