Can't manage media on iPad on iTunes

I used to be able to sync movies, TV shows, etc. on my iPad (and iPhone) through iTunes. At some point (perhaps around the time I had to do a factory reset on my phone), I lost the ability to do that. I can connect both devices to iTunes, and it will recognize them, but it doesn't show any media available to sync. Both iTunes and my iPad are logged in to my account (I can see movies available on each device), but if I check the box to sync, say, movies, it will not show any movies available. (It does show podcasts are available, though, if I go to that tab.)

iTunes also doesn't recognize any movies or TV shows already downloaded to my iPad.

I tried logging out and back in on both my iPad and iTunes, but still no luck. I decided to wait until iOS 12 came out to see if that helped, but nothing changed. I'm usually good at figuring these things out, but is there something I'm missing to be able to sync though iTunes?