I've posted another Yahoo! Shopping API related request here as well and requested access to the YDN-store (a couple days ago), but I'm not sure that any of it's being seen/attended to. My request is similar to this one in that it has to do with a seeming malfunction of the Yahoo! Shopping API.
Since the Shopping group is no longer around, it does seem like the best place to ask is the Store group. I know that the team in charge doesn't visit this forum much, but watches the groups so that's the best place :)Community Manager, YDN