No thanks to AW who, after 36 hours hadn't answered my email, I found the problem. Ebay now requires some listing categories to include a UPC code. With older items I don't have a UPC code available so I left it blank. The field in AW is a drop down box yet no default inputs appear. Since I now find that this field is MANDATORY, and appears to be the reason my items were not being listed, this drop down box needs to have some input that ebay will accept. If, in this field you enter 'Does Not Apply' ebay will accept the listing - that's all there was to it. I hope this helps some of you having this problem as it took me many hours of frustration, research and trial and error. Such a simple thing for AW to correct! Why didn't they do it?