Core/Movement: minor MotionMaster refactor (#18367)

src/server/game/Entities/Unit/Unit.cpp

@@ -386,6 +386,7 @@ void Unit::Update(uint32 p_time)
 
     UpdateSplineMovement(p_time);
     i_motionMaster->UpdateMotion(p_time);
+    UpdateUnderwaterState(GetMap(), GetPositionX(), GetPositionY(), GetPositionZ());
 }
 
 bool Unit::haveOffhandWeapon() const