How to resolve 'You don't have permission' error when exporting from Photos app on iPhone?

I’ve attemped to export all photos and videos as unmodified originals from the Photos app on my iPhone to an external exFAT hard drive, but I get the error: "The file 'xxxx.JPG' couldn't be opened because you don't have permission to view it. You don't have permission.”

However, when I search for "xxxx" in Photos, no such file appears.

Has anyone else experienced this or found a fix?