Plex does not yet support ATSC 3.0 stations. This is primarily due to missing support for the AC-4 audio codec which is utilized by ATSC 3.0. As of right now, there is no way to use these stations with Plex’s Live TV & DVR feature. There’s a fairly active discussion in the thread linked below.
Also, when it does become supported, you will need to map your non-ATSC 3.0 equivalent channels to the ATSC 3.0 ones in the EPG configuration. For example, if you have ATSC 1.0 channel 4.1 and the ATSC 3.0 equivalent 104.1, you would assign 4.1’s guide to 104.1. This is due to the fact that the 1XX.X channels are constructs created by SiliconDust so that there wouldn’t be duplicate channels presented by the tuner.
