iMovie export fails with Ring camera footage on iPad Pro

I’m looking for some technical guidance on an iMovie export issue involving Ring camera footage.

Devices and setup

iPad Pro running the latest iPadOS

iMovie for iPad, latest version

Two Ring Outdoor Battery Stick Up Cams

Source files downloaded from the Ring app as MP4 files

The MP4 files import into iMovie successfully. I can preview the clips, scrub through them, trim them, edit them, and build a complete project without any obvious issue.

Issue

When I try to export the finished project, either to iCloud Drive, photos or directly to YouTube, iMovie fails and shows an error message. This wasn’t always the case until recently (few months). The same issue presents even if I download from Ring desktop to iMovie on my MacBook Pro.

Current workaround

I transcode the Ring MP4 files into new MP4 files using a free converter before importing them into iMovie. After transcoding, the same clips export correctly. This seems to be a problem in the way Ring encodes the original MP4 files, possibly the video codec, audio codec, variable frame rate, container metadata, timestamps, or some other compatibility issue with iMovie on iPadOS.

Has anyone else seen this with Ring camera footage in iMovie? Are there known issues with Ring MP4 files and iMovie export on iPadOS? Is there a way to fix or normalise these files on the iPad without manually transcoding every clip first?

Ring support was unhelpful and said it was an Apple issue, so I’d be grateful for any technical suggestions.

Thank you so much.