Finder will not copy files to a new location. Error message says 'file already exists'...but it doesn't.

This problem has started occurring in the past week (24/05/2021) and since occurred several times across multiple network shares, volumes and local locations on my iMac (Big Sur 11.3.1), only when performing copy and paste in Finder.

When copying files to a NEW folder or location an error message displays saying that Finder cannot complete the operation because the file already exists in that location. It/they do not and have never existed in that location as the location is new i.e. a new folder or a different drive* etc.

The only clickable option on the dialogue box is 'OK' (i.e. no Replace, Skip or Auto Resolve etc.).

I repeat that on all occasions that this has occurred I have been trying to 'Paste' the copied files into a brand new folder and/or on a completely different local drive or network volume to the original files. This is happening across multiple types of network shares, volumes, local disks and cloud locations that sync to a Finder folder e.g. dropbox so no need for questions that are guessing at a problem with the location I am trying to copy and paste to thanks.

If I keep trying to paste the copied files into the desired location this pattern occurs:

1. First attempt to C&P = no files can be pasted, error message says files already exist and the only option on dialogue box is OK to exit the error message.
2. Second attempt = Finder gives the options to Replace, Skip or Auto Resolve for ONE FILE ONLY (1/3), even if Apply to All is checked the other two files are shown with the same error message as above. The first file is successfully pasted into the new location.
3. Third attempt = second file is executable via the Replace option. 3rd file receives the same error messages as at (1). The second files successfully pasted.
4. Fourth attempt = third file is pasted using the Replace option...
5. ...and so on.

This is also happening with various file formats.

Thanks in advance to any with useful insights.