I had same problem and sorted it using this thread. My problem was that I had inadvertently mapped my NAS twice some time ago on my MAC and a couple of the movies were copied across to the NAS using the second mapping. I tidied up my machine and removed the additional mapping but I had both directory structures in my library still. When I delete the movie from the NAS the library couldn’t update presumably because it could no longer find the directory that the movies were supposed to be in because they were copied using the one I had since removed. Once I removed the 2nd older from the library it refreshed properly. Would be better if PLEX gave an error message or warning if it can’t find a particular file when refreshing or emptying trash.
