Same problem - I've been waiting over 7 hours - and it still says waiting to upload and image. I have a 150Mb connection. Perhaps some part of the Apple cloud is down? AJ

Not fixed : I've trying for over an hour to get just ONE screenshot uploaded out of 80. ) Hangs on IE, Chrome, Safari, Opera ) Hangs for Jpg, Png. HEIC does not work ) Refresh get you nowhere. ) Changing menu within the the Gui and returning - wipes your picture. Bizarre.