servers no longer listed in Steam Master Server List

Just wondering if anyone knows of/or is having issues with the steam master server list.
recently my 4 servers have disappeared from the steam master server list. I still have sv_reagon 5 in all my server.cfg
2 servers are with one game provider and the other 2 with another, they were all on the master list up until 2 weeks ago.
I can find them by adding them through my favourites, however they still never appear in the master list.
I have contacted my game providers to ask if their was firewalls or anything added, Both the providers say that that no firewalls have been added, and other clients of the on the same ip are still visible.

Any Ideas on how to trace this problem, or anyone else suffering the same issues recently.

and...

http://forums.srcds.com/viewtopic/13866