Hey sdean5a,
Thanks for the update. Since it seems to happen to only half of the downloaded movies, you may need to delete and download the movies again.
Are these movies downloaded from the iTunes Store?
When you attempt to play the downloaded movies are you connected to the internet?
"How to redownload movies and TV shows on an iPhone, iPad, or iPod touch
- Open the iTunes Store app. Sign in with the same Apple ID that you originally used to purchase the item.
- On an iPhone or iPod touch, tap More in the menu at the bottom of the screen, then tap Purchased. On an iPad, just tap Purchased.
- At the top of the screen, tap Movies or tap TV Shows.
- If you use Family Sharing and you want to see content that a family member purchased, tap the family member’s name.
- Find the movie or TV show that you want to redownload, then tap it.
- Tap the download button for the title. When the download completes, you can find the movie or TV show in the Apple TV app. Don't see the item that you purchased?"
Redownload apps, music, movies, TV shows, and books
Have a good one.