Repro:
set up an AA (f.e. Praetorian) and a player.
praetorian = yourPraetorian;
_turretPaths = allTurrets _praetorian; //[[0]]
_turretPath = _turretPaths select 0; //[0]
_praetorian enablePersonTurret [_turretPath, true]; // optional
player assignAsTurret [_praetorian, _turretPath]; //optional
player moveInTurret [_praetorian,_turretPath]; //should work but doesn't
//player moveInCommander _praetorian; //ofc doesn't work
//player moveInGunner _praetorian; //should work imho
//player moveInDriver _praetorian; //should not work