Most of my sites on EPN only show clicks and no impressions. But starting the 5/9, one of my sites started showing impressions. After looking at various reports, I've identified that the impressions are coming from a "Creatives Generator - eBay_Dynamic Listing_160x600" and not the standard "RSS Generator". But I have not placed such a banner on that particular site. I've also looked at all of my sites to see if I placed it there with the incorrect campaign id, but no luck. How can I track this down?
Well your RSS feeds should not give you impressions, that's ok. As far as tracking the mystery impressions, I would guess that you built an eBay_Dynamic Listing_160x600 with this store's campaign number and then put that ad on a different site. Check all of your eBay_Dynamic Listing_160x600 ads and see if the campaign number matches the site with the impressions that are showing up