I’ll add another layer of complexity to the on going poster problems with plex.
I created this thread 1954 movie Sabrina has blank artwork on en-GB watch.plex.tv which alas has been ignored.
However, as you can see even with the new gracenote metadata provider they are blank. However, what is bizarre is that even with local poster assets I ended up with blank posters on my local server. I had to rename poster.jpg and fanart.jpg to something different (1poster.jpg and 1fanart.jpg) force refresh the metadata and the rename them back again to get plex to pick them up correctly.
Something funky is afoot.