Before anyone points out that this post may be in the wrong forum there has been a thread running for nearly 12 months now in the WHS Forum concerning greyed out clients in the WHS Console;
http://forum.avast.com/index.php?topic=41082.0
It would be nice if someone from Alwil were able to respond rather than leave us all in the lurch…it seems rather cold down there in the forgotten forum… :
The only official response was from vlk last January asking us to report back if we were still having the issue - since then the thread has grown to 4 pages of users with the same issue but absolutely no further response from Alwil whatsoever… 
I did email support last December around the same time as the OP in that thread but received no reply… >:(
Thanks & regards,
-=Glyn=-