I'm using the Northeme theme slider. My thumbnails were displaying nicely under the slider – square, correct theme padding and good resolution. For some reason they are now rectangular and the overlap each other at the edges. From what I can see the slider thumbnail settings are still portrait and 300 pix. This is since I built a media gallery on another page (using the add media tab). I've now deleted this in case there was a conflict. I've tried regenerating thumbnails but no difference. Please help.