Class member variable would not update
I figured it out.

I was passing the engine objects as references instead of pointers.

main.cpp

// Engines
engine::Engine
    engine1(motors::Constants::MOTOR_1, motors::Constants::MOTOR_1_FORWARD, motors::Constants::MOTOR_1_BACKWARD),
    engine2(motors::Constants::MOTOR_2, motors::Constants::MOTOR_2_FORWARD, motors::Constants::MOTOR_2_BACKWARD),
    engine3(motors::Constants::MOTOR_3, motors::Constants::MOTOR_3_FORWARD, motors::Constants::MOTOR_3_BACKWARD),
    engine4(motors::Constants::MOTOR_4, motors::Constants::MOTOR_4_FORWARD, motors::Constants::MOTOR_4_BACKWARD);


engine_controller.cpp init list

EngineController::EngineController(engine::Engine &amp;t_e1, engine::Engine &amp;t_e2, engine::Engine &amp;t_e3, engine::Engine &amp;t_e4)
    : m_engine1(t_e1),
      m_engine2(t_e2),
      m_engine3(t_e3),
      m_engine4(t_e4),
      m_currentSpeed(EngineControllerConsts::MAX_SPEED),

      // Directions
      m_rights(0),
      m_lefts(0),

      m_rightDistance(-1),
      m_leftDistance(-1),

      m_lastForward(true),
      m_counter(0),

      m_lastForward1(true),
      m_lastForward2(true),
      m_turnsCounter(0)

{
}


The solution would be to use dynamic memory allocation.

main.cpp

// Engines
engine::Engine
    *engine1 = new engine::Engine(motors::Constants::MOTOR_1, motors::Constants::MOTOR_1_FORWARD, motors::Constants::MOTOR_1_BACKWARD),
    *engine2 = new engine::Engine(motors::Constants::MOTOR_2, motors::Constants::MOTOR_2_FORWARD, motors::Constants::MOTOR_2_BACKWARD),
    *engine3 = new engine::Engine(motors::Constants::MOTOR_3, motors::Constants::MOTOR_3_FORWARD, motors::Constants::MOTOR_3_BACKWARD),
    *engine4 = new engine::Engine(motors::Constants::MOTOR_4, motors::Constants::MOTOR_4_FORWARD, motors::Constants::MOTOR_4_BACKWARD);


engine_controller.cpp init list

EngineController::EngineController(
    engine::Engine *t_e1, engine::Engine *t_e2,
    engine::Engine *t_e3, engine::Engine *t_e4)
    : m_engine1(t_e1),
      m_engine2(t_e2),
      m_engine3(t_e3),
      m_engine4(t_e4),
      m_currentSpeed(EngineControllerConsts::MAX_SPEED),

      // Directions
      m_rights(0),
      m_lefts(0),

      m_rightDistance(-1),
      m_leftDistance(-1),

      m_lastForward(true),
      m_counter(0),

      m_lastForward1(true),
      m_lastForward2(true),
      m_turnsCounter(0)

{
}