I just started with Emby last week (server version 18.104.22.168) and all has gone well until I tried to play an OTA recorded video that Emby reports as 1080i mpeg2 on a Roku streaming stick. Other OTA recordings at 720p mpeg2 have played fine. I get a black screen with a progress bar that jumps part way initially, then quickly disappears. Emby appears frozen after this happens and I can only exit by pressing the Home button on the roku remote. I have the video quality in the Emby roku app set at 720p HD 2mbps. Tried changing it to Auto with same result. Also messed with Roku Streaming Stick 3800RW / 9.1.0 video quality settings which is currently on auto detect 1080p, but I have tried 720p as well in an attempt to lessen the load. BTW the video plays fine on Windows 10 server through the Emby web interface.
Here's the activity shown in the web dashboard, even though file did not play and I exited Emby as described above.