All photos I put into the media library are showing properly except for the larger sized photos. The larger photos are showing up gray in the thumbnail. The large photos do show up when I click on the image to see Attachment Details and do show up in the post but not as a thumbnail.
Regular photos are 700×1050 and the large photos that are gray are 700×1400.
What setting do I need to change to have the thumbnail images show in the media library?