Can't remove a gallery image
I have a school website which is about to go live and teachers are already uploading to the gallery. After a batch upload, a few of the images show empty thumbnails on the album page as they have not uploaded correctly. Not a problem if they could re-upload them, but I can't seem to remove the traces of the old ones as they ar enot showing up in the backend, only an the front end pages as missing images. Any help would be appreciated.