Can you go to chrome://flags in the address bar
and set "New Media Controls" (#enable-new-media-controls) to "Disabled" ?
If that works, then I know what to change by default
I closely followed development of these new media controls (I am working on gestures for media playing), and they seem to be very buggy so I wouldn't be surprised if they were the cause of the fullscreen not ok.
Note: maybe it's not related to media controls, but I strongly suspect it.
Let me know if this solves the problem,
Btw, yes of course I want to fix it that's a major thing