Chromecast to Tivo (Plex releated)

So I just accidentally discovered the other day that you can use Chromecast to cast video to your Tivo Roamio. When I was pulling up the chromecast option, my Tivo showed up as a choice and I clicked on it and it started playing - very cool.... However, I did notice something and I was curious if anyone else knows anything about this ->

Using the Youtube app (Android), when I go to use Chromecast, the Tivo is an option and works.... But when I try and use Chromecast from the Plex app (Android), the Tivo device does not show up. With the Plex app, only the actual Chromecast device is listed. Anyone know why this is?