Clips "going black" when attempting to share to a file
I've noticed that when I recently added movie clips from my iPhone to a project in iMovie, the "break" the project when I try to share to a file.
I get an error message after a while when creating a file, and I've noted that, consistently, the file terminates before an iPhone video in the sequence. When I go back into iMovie, the clip "goes black" and can't be played (audio or video). Taking out the clip allows the project to be rendered to a video file... until it reaches another iPhone video....
I added them to the timeline in iMovie from within the app, so I'm not sure why they're breaking.
Anybody else having this issue?
iMac 21.5″, macOS 10.15