Roku Won't Playback Certain H.264 / MKV (or MP4) Container Files when transcoding is needed

[Mr_Noodle]

You seem to be having the same issue as me. The latest update in the beta channel seemed to fix it for me.
My original post:
Roku has to retry multiple times to get MKVs to play - Plex Players / Streaming Devices - Plex Forum