Just seeing this topic, same issues for me and I am recording directly within Emby.
My thread is here for additional logs/details:
I noticed after reading this thread my issue files all also happen to be 1080i MPEG2, so very possibly related. I have seen it on 720p MPEG too as well last weekend, but this weekend all affected files were 1080i MPEG2 just like OP.
Newest discovery was that my Roku will play these while recording is still in progress, but once recording is complete it will not play anymore until I convert it. Files play fine without conversion within the Emby web app.
This is on 126.96.36.199 Emby, Roku Beta and Stable have the same behavior.
Edited by bizarro252, 17 September 2019 - 12:18 PM.