NuGet Feed not using latest artifacts

I recently ran a build config with a new artifact.  This artifact had some issues with it so I made the correct changes to the file and switched the old, bad artifact for the new, correct one.  However, our NuGet feed is still using the old artifact, even after a force clean!  The old artifacts are gone from our build history and only the 2 most recent build configurations have their artifacts.  Both of the recent build configs have the correct artifact.

Why are these old artifacts still present in our NuGet feed?  How can I get my new artifacts to show up?

Thanks.