When I play a recorded programme it freezes as the actual show starts.
Say the recording was scheduled for 19:00… after adverts etc the show theme tune plays at 19:03… as soon as the theme tune stops and the episode starts then the picture freezes. The audio continues.
The only way around this that I can see is to allow it to play for sufficiently long (30 secs?) then close plex, reload and click on Resume. Then the video plays as normal