I've made a map with the type TM_Stunt for the colors, then changed it's type inside the Trackmania editor to TM_Race, validated, saved, then opened in GBX Explorer and changed `CGameCtnChallengeParameters->MapType` value to `TrackMania\TM_Stunt` so it could be played as a race track while keeping the stunt colors.

Everything works in game, but the map cannot be uploaded to TMX. It gives me this as soon as I try to upload the file:

... says:

Unexpected Runtime Error
Something went wrong:
Input Not Consumed

This should be fixed now.

Yup, it's indeed working.