You have a great template (the best probably). My template was rejected because my cover had the same (similar) issue as these pictures. I debug my <figures> everything is proper. I inspect the result the link is in <alt> attribute, while the src is empty (no errors in the process). This message is my way of asking the IV authorities about all of it. Maybe there are multiple links for cover images, but there aren't doubles for every image (this issue is global). Why templates are held accountable when it is probably a tiny bug in IV Code? Template's part of the pipeline seems good. If it is a bug and it will be found in a couple days, will rejected Templates be returned to their fair place?
P.S. here you have a little bit different issue, but you know what I am talking about considering you have your covers handled. And again, you template is great and please don't resubmit it before the response I am waiting. Best wishes)