I had recently moved my server from Linux to Centos along with the metadata folder(s). After the move everything came up and worked. Only problem I had was multiple not all Collection folders were messed up. The Posters were only showing one poster and not the collection 4 posters. This is due to one of the movies in the collection losing the default poster even though you can see the poster in the collection.
I resolved this problem by going into that movies collection and edit the default poster for the movie you do not see in the collection poster. Most of the time only one movie had a default poster selected. I went back to main collection page and edited the collection poster. Now sometimes it may show the same single image, the new 4 poster image or sometimes a black box. Just go ahead ahead and select the poster and hit save. Then went back out to the main collection page and after 5 seconds are so the collection poster changed to the 4 poster view.
This also holds true to a black poster on the collection page if there is only one movie for that collection so far. This means the single movie lost its default poster image. Go into the collection. Edit the poster for that movie. Back out to the main collection page and edit the poster for the collection, if the image doesn’t display after 5 seconds.
If you still have problems just delete the collection go to each movie and re-select the default poster and re-add the collection. But the above steps should do it.
