This has been a problem I’ve had on any Source game. My server will never appear on the server list.
I’ve tried sv_lan 0 and I’ve double-checked that the proper ports are forwarded, and I do have a static IP. All the ports are forwarded to my static IP.
I find it very odd that I can host on any game that requires port forwarding except Valve games.
I would also check to see if there’s another thread that explains this but unfortunately the search button has disappeared.