Can't export photos after migration to Monterey
I recently migrated from a macbook pro running 10.14.6 to the latest Monterey 12.4 running on a M1 mini.
I used migration assistant to transfer my account, apps, etc (everything that MA could migrate was migrated). A large library of photos (in Photos.app) was migrated. The library has many annotations, e.g. titles, keywords, edits, descriptions.
When I open the Photos app on the mini the library looks OK. All the photos can be opened, the original annotations are still intact. On the surface it looks like everything has been migrated properly.
but...
I tried to export some photos from the library and got this message:
Export Complete with Errors
0 (of 1) files have been exported.
The export operation failed to create a file for the photo identified below:
..
IMG_4698.jpg The operation couldn't be completed (Cocoa error -1.)
This error only occurs with photos migrated from 10.14.6. Photos that were imported directly to the mini in the last few days, i.e. not migrated, can be exported without problem. SO I know that Photos is set up correctly with the correct permissions and the folder to which it is attempting to export is writable by Photos.app).
I do not have these photos on iCloud. I do have the photos on the macbook pro, so if I was really desperate, I could upload them to iCloud and try to completely recreate the library but that would be a long project.
I have no idea how to fix this, but I need to be able to export from my Photos library.
Please help.
Mac mini, macOS 10.12