Question: Finder will not finish copying file open in another application
I had just downloaded photos from my iPhone via Photos on MacOS and while I still had Photos open, I used Finder to locate a particular photo and use the Finder Duplicate function on it. A progress bar came up for copying and it never went away. The "copy" file remained greyed out and when it is selected the preview in Finder shows a grey spinning busy wheel.
I've tried many actions to get this to clear up. Quit photos, relaunched Finder, rebooted. The file cannot be deleted. After reboot, the busy wheel still spins.
What can I do next to fix this?
MacBook Air, macOS High Sierra (10.13), mid-2012