Game only supports 24 gamemodes
As far as I am aware with the current gamecode only 24 gamemodes are supported as a bitflag is used to check which gamemodes a map supports:
if((MapInfo_Map_supportedGametypes & MapInfo_CurrentGametype().m_flags) == 0)
return 0;
When adding more than 24 gamemodes to the game (not hard as the base game has 20 already) the system will fail to pick the correct gamemode and select a random one instead.
For example, this happens when switching to dance:
can't play the selected map in the given game mode (ctf). Falling back to a supported mode (cts).