Since it has been a while since you’ve been active on the forum, maybe you missed this update: GameModes v2.0.0
Voting was changed so that by default, everyone in the lobby has the equivalent of /vote on a random map (picked at the start of intermission). This means in a 12 player lobby, if only one person manually uses /vote, then it’s a 1/12 chance that their vote is the one that is picked.
On the other hand, in a 2 player lobby, if both players use /vote the map that is picked should be one of the two they voted for.