I thought I would give this post a bump as I am experiencing the same difficulty. My images fit the guidelines but do not upload either.
I wonder if it is due to the new provider art guidelines that will be required for iTunes v11 where images must be 3200 x 600 pixels??
I am hoping that when iTunes 11 launches the problem will be resolved - fingers crossed.
Still, any tips to get art work uploaded in the current form are very welcome.
Same thing here. We have the images: correct images size, extenion, RGB colors, we followed guidelines multiple times, Still nothing we can not get them to show.
We even tried uploading images that were incorrect, in this case we get an error message.
When we upload images of the correct size we do not get an error message but no images appear.
We have even tried with different versions of Safari and on a PC or MAC.
We have no idea how to fix this. Any help would be MUCH appreciated.