iMovie Theater on Mac won't play movies
I recently cleaned my Mac and installed High Sierra. After syncing with my iCloud account and loading iMovie, I noticed that I wasn't able to play movies in Theater that were in the cloud. I can see my movies but they are grayed out. When I click on one, it says "<Movie Name> could not be found." I am able to play these same movies from my iPhone and Apple TV without any issues. If I add new movies to the theater from my Mac then they work fine across all devices including the Mac.
Any ideas how to fix this?
iMac, macOS High Sierra (10.13.3)