TV App Won't Add/Sync/Delete Movies

[iMore Question]

Iphone 7 - most current OS. Hate this TV app! Aside from artwork that's too big to scroll through a huge library of movies on my phone.... I can't add or remove any movies from my iPhone. If I drag and drop while my phone is connected to my iMac, anything I drop is greyed out on the phone. Phone has 58GB of storage free. This isn't specific to certain movies. I have a huge library and nothing is working... HELP ME PLEASE!!!!