make sure you have selected the way you want the downloads to proceed as there is an option in windows update /settings/ to download updates ;;but only installed by user so could be awaiting your approval?
probable best to set this to auto download and set a time
This is known to help in some cases : Go to Internet Options > Security Tab > 'Trusted sites' icon > click Sites then uncheck 'Require server verification'. Now add these 2 sites http://*.windowsupdate.microsoft.com and http://*.windowsupdate.com. Click Close, Apply and OK.