Using (regular) WSUS it is stuck forever (more than 48 hours) on checking for updates. Actually I have 2 servers (both with Exchange 2013 CU13 on them), that are in the same situation. As the title says they are running Windows Server 2012 (NOT R2).
I figured okay WSUSOffline will surely help, then they will get the magical update they are missing and all will be well in the world (they were last updated about 6 months 5 months ago). I ran wsus0ffline for over 12 hours and both machines never left "Listing IDs of missing updates...
I know it will take a while but I imagine 12 hours is more than enough.
What am I missing? How can I get these machines to update! Like I said 5 months ago updates worked without any problems. They both say from WSUS (actually one I deleted the catalog etc so it claims to have never been updated) but they both were fine with WSUS until about the 16th of April...