Fooling around with the Mini, connected to XL4, both running current software. Haven't tested these all on the Premiers, too tired atm, but I think most of these happen on both.
under 'what to watch now'...
-the entries will show like 'live' 'xfinity' (on demand) and 'amazon' under the description, but there doesn't appear to be any way to select your source that I can discern, it just tries to tune the live tv channel when selecting the item. (why list em if you cant get to em?)
-when selected, some of them just drop you to live tv, back to whatever station you were tuned to last. Some of em go to strange places like music choice stations when it was a movie.
-it doesn't tell you anywhere what station the item is on, which would probably be better use of the space where the sources are shown, since you cant pick your source anyhow.
under 'browse tv and movies',
-under tv, suggestions... its empty. and then it suggests you 'hit enter to review thumbs', which is also empty. (this one does definitely work on the premiers)
-if you go into either collections or tv, then a category, then pick a item... it doesnt work well. movies seems to work fine. For a random example, pick tv, best comedies, then click on 'Cheers'. It shows tv, netflix and amazon as sources. But, when I go into the show, I get 'get a season pass' and 'record next episode' as the only choices, no way to get to netflix or amazon! (or hulu, etc). If you find a choice that live tv isnt available, your only option will be to make a wishlist, even if it is telling you there are other sources available.