This is likely because the originating stream is H.265, which cannot be played by many browsers.

A quick internet search will reveal what browsers currently support playback of H.265.

Compass allows you to change the Web Quality, which will convert the stream to be viewed by the browser. If it is a h.265 stream, Compass will automatically detect it, and give the user an option within Web Quality to Convert to H.264 , which will convert the video, while keeping the other video attributes, the same as the source.