Every time I attempt to move a group of photos from one folder to another (via drag-drop on my MacBook Pro 13" 2017) all bar one photos move. The remaining photo generates an error. If I try to move it again it generates the same error. Checking the folder in Finder shows that it is still in the original folder. Closing and restarting LR has no effect. This keeps happening and to any moves from any folder. Only a recent problem.