hmm, I still can't see it even if I go through the normal ut3 menu.
I checked the mapmixer config file. There is this line:
ClientGameTypeHelpers=(sGameClass="Jailbreak.Jailbreak",bLeaderStatusNotification=True,bHUDLeaderboardDisabled=False,fHUDLeaderboardPercTop=0.450000)
and these lines:
[Jailbreak_Jailbreak MapMixer_DataGroup_GameType]
Options=(sGroupName="Rules",sURLName="GoalScore",sName="Goal Score",eType=mmOT_Int,sData="0:9999",sDefaultValue="3",sDescription="Set the Capture Limit for the match. 0 means no limit.")
Options=(sGroupName="Rules",sURLName="TimeLimit",sName="Time Limit",eType=mmOT_Int,sData="0:999",sDefaultValue="20",sDescription="Set the Time Limit for match.")
Options=(sGroupName="Rules",sURLName="QuickStart",sName="QuickStart",eType=mmOT_Bool,sDefaultValue="False",sDescription="Toggle whether or not to start the match immediately.")
Options=(sGroupName="Rules",sURLName="demo",sName="Record Demo Filename",eType=mmOT_String,sDefaultValue="",sOptions="Demo-DM",sDescription="Enable Demo Recording by entering a target demo filename. Leaving it blank disables recording.")
So it's obviously detecting something!
EDIT:
I take it back now the gametype is showing up in the list when I go through the normal ut3 menu. However whenever I try to start a match the game starts as a deathmatch rather than jailbreak game.