@jess I think there is an update to google chrome that prevents the html5 player from entering fullscreen.
Please provide the player and Chrome versions in question.
If you can also provide a URL where said player is embedded, that would be most beneficial.
The stable version of the player is currently v2.73.2 and it includes the needed fix. Please upgrade.
Thanks @jess it works now. One more thing though. Is there a way to force the html5 player orientation to landscape in fullscreen on mobile devices? I tried setting EmbedPlayer.EnableNativeChromeFullscreen to true. This works but all the html5 player controls gets replaced by the native player.