360 video playback on GEAR VR with Google Chromecast

Anybody having issues with this? These are videos I'm creating myself, which playback fine in the headset but I get 'something went wrong, we can't play this video' message after I launch 360 videos from the oculus app using the chromecast feature.

EDIT

If anyone's interested I fixed this by changing the size of the mp4 to 3840x1920 - it seems the chromecast doesn't like 3840x2160.