Missing update in WSUS

Here I've got a WSUS and ~20 Windows 8.1 x64 Client.

I deploy allnecessary update to the client.

I test different clients with Microsoft Update and now they reports the following updates missing:

KB3005628

I approved this update but no client installs it

KB2976978

I didn't find this update in WSUS

Is this behavior normal?

Must I install those updates manually on all clients?

Thanks

Reto Felix