Here is a link that you might be interested in trying. It us using Zap2xml for multiple program sources. Myself I just don’t have the time to play with it and I am really hoping that Plex gets this fixed. That was one of the main reasons I went with Plex Pass lifetime was the capability of recording my ota shows using HDHomerun tuner. If I can’t use the guide, I can’t even view the shows.
[How to use zap2xml for Plex EPG & combining multiple EPG sources]
