I can see Servers in the Steam Server Browser but not in the Game Server Browser.
How do I fix this?
If servers appear in Steam Server Browser but not in the Game Server Browser, the issue may be caused by a firewall that is blocking the game's .exe (hl2.exe, left4dead.exe, etc.) from properly accessing the internet.
You need to remove all permissions for Steam.exe and all of the game .exe's and then, either re-add them or allow the firewall to discover them again when you re-launch the Steam games.
Please also try disabling any programs that may interfere with Steam.
Additionally, make sure all required ports for Steam have been allowed.
In some cases, this issue can be resolved by deleting all files in your Steam installation folder except for Steam.exe and the Steamapps folder.