I originally reported that it appeared the only way to get the HDHomerun Premium TV content to play on Plex was via HDHR Viewer 2.
However, it appears Lon Seidman over at Lon.tv has found the solution! Check out his solution below. I followed his steps, and all works well for me! Thanks Lon!
Keep in mind, this solution isn’t without its flaws as well (as Lon points out). Some channels may need to be manually mapped to the Guide, and even then I have found that even some of those continue to show incorrect channel content.
Either way, at least we have a couple temporary solutions!