Just to update, I figured it out. I was trying to add Episode IDs to the playlist. You can only add Movies, Series, TV Specials, or Short Form Videos to a playlist. It would be nice to be able to make a category on my homescreen that could show individual episodes but I don't see a way that can be done in Direct Publisher. A klugey way would be to create a series with just one episode per series. Another way would be to create movie objects instead of episodes, but I'm not sure how that affects ROKU search... will people think my tv episodes are movies...
For now, I'm abandoning trying to display episodes on the home screen and instead showing series tiles.
