So I just picked up a new Nvidia Shield TV and have been playing around trying to get everything figured out. I've been banging my head against the wall trying to get apps to sync correctly.
I logged in with my Google account and right off the bat I noticed that YouTube was showing me recommended videos from channels I subscribe to, but when I scroll down to subscriptions, the menu is completely empty. I also noticed my playlists are not populating as well. The sections are there, they're just empty.
Google Play and Music both appear to work correctly, but the Photos & Videos app is a complete mistery to me. All I see when I open the app is a black screen. There's a slide-in menu on the left with a few options as well, but it's not actually pulling down my content.
Initially I thought it would just take some time and figured I'd give it a day or two to sync up. It's been 3 days since I set it up and logged in and these two apps are still void of my content. Any ideas?
Not sure what's wrong with your YT, but the photos and videos apps is only for local content.
Try clearing data for the YT app and see if it pulls your account data.