Okay, I've got sourcemm running, however it changes the game name to "Half life 2: Deathmatch", rather then what it should be, "Sourceforts". I am able to reproduce this quite easily :/
Got some more info on this: Sourceforts starts out as the game name being HL2DM, and changes it to Sourceforts after its loaded. Sourcemm apparently isnt catching the fact it changed, so it doesn't forward it to the server.