Do not have permission to open certain files after having been copy/pasted from another folder

Recently I copied a few files from one location on my Mac (OneDrive personal folder) to another location on the same volume (Documents folder), and I am not able to open *SOME* of these files.

I am getting a permissions error stating that I don't have access to the file, however I clearly do. I have checked file permissions and ownership which are correct, and run First Aid on the disk (Repair Permissions has been removed from Disk Utility - among many other things).

1. I open the source file no problem
2. I copy the file and paste it into the destination folder
3. I try to open the file but get access denied

What's extra strange is that this doesn't happen with all files in the same source folder - just some of them.

'ls -l' in Terminal is showing that many files have [extended] file attributes, however most of them open just fine.

This problem surfaced on macOS Mojave, and I have just upgrade to Catalina. Issue is the same and common files to the file access problem are still not working.

I am happy to re-copy the files (and not fix the permissions problem on the copied files); however the copy process is clearly doing something that it shouldn't be.

Greg