Please see my reply on the other thread. The patch that I think might fix the issue, Bug #36721: Discovery Provisioning fails as the sync media is getting diminished from the host page even though it's synced - Katello - Foreman, has now been triaged for Katello 4.9.3, which means that when @wbclark does the next 4.9 release, it will be included. However, that same fix is also in Katello 4.10.0, so ideally you could try upgrading to that.
