WSUS console don't visible few workstations...

Few minutes show in console after execute this commands:

net stop wuauserv
del "C:\Windows\SoftwareDistribution\*.*" /F /Q
net start wuauserv

wuauclt.exe /resetauthorization
wuauclt.exe /r /detectnow
wuauclt.exe /reportnow

Then it is invisible workstation is WSUS console. Can't found! Few computers is visible, but more don't visible!

Where is error?

Thanks!