Some WSUS users reported an intermittent sync problem shortly after the release of the April 2015 security updates. This issue may have temporarily affected WSUS administrators' ability to sync released hotfixes to their top-level WSUS servers. Although the workaround in this article was published, and Microsoft support professionals quickly investigated the reported problem, the cause of the sync failure has not been determined.
No issues have been reported or connected with the May 2015 security update release, and there are no additional details to report. Microsoft will continue to monitor for any signs of the problem's recurrence.