You could try change back in default value.
Code:
// Specifies when to start the vote based on time remaining.
// -
// Default: "3.0"
// Minimum: "1.000000"
sm_mapvote_start "15" // Those are minutes.
// Specifies when to start the vote base on frags remaining.
// -
// Default: "5.0"
// Minimum: "1.000000"
sm_mapvote_startfrags "40"
// Specifies when to start the vote based on rounds remaining. Use 0 on TF2 to start vote during bonus round time
// -
// Default: "2.0"
// Minimum: "0.000000"
sm_mapvote_startround "10"
If not help, then need look your game settings.
*edit
Look mapchooser cvar settings again:
rcon sm plugins list -look mapchooser index number
rcon sm cvars index -you get list cvars