error -536870181 and weird problem with optical flow on M1 Ultra

I’m also having significant problems working with ProRes on the Ultra.

• Export times from Apple Motion have become interminable—for instance, 3 hour to export a 30 min 1080p file.
• After spending ridiculous amounts of time exporting, the file simply disappears when the export is finished. No trace of it anywhere.
• Exporting to H264 works, but more often than not the audio is out of sync.

I think this began with the recent OS update. I’ve found some bug reports on the Apple Dev forums relating to ProRes.

The entire impetus to purchase the Studio Ultra (with its high price tag) for my video work was to be able to get more work done. Now I’d be better off with the old Intel machine I traded in. 😤

The first thing whenever the application is misbehaving is to delete the preferences.

To delete preferences, hold down command and option while starting FCP X and click Delete Preferences. The application will start in a default state, and open an “Untitled” library.

Reopen the library you were working on, set the preferences the way you like them, and try again.

Also, delete all render files.

If the problem persists, there could be some bad media of a subtle corruption in the project? Do other projects export?

You could copy everything, make a new project, paste. Does the new project work?

It looks to me like your problem may be a different one than the OP’s, so you should start your own thread and include a full Etrecheck report. Problems when upgrading the OS or moving to a new mac - especially one with a different architecture - are more often than not due to old stuff migrated. The Etrecheck report often gives us a good idea of what may be the likely cause.