TB6612FNG Motor driver does cannot run motor backwards

Other Hardware Motors, Mechanics, Power and CNC
1

I'm using the arduino nano with the TB6612FNG motor driver.
Here is the code i am running:

#include <SparkFun_TB6612.h>

Motor motor1{3, 4, 5, 1, 9};
Motor motor2{7, 8, 6, 1, 9};

uint8_t pwmSpeed;

void setup() {
    Serial.begin(9600);
}

char recv{};

void loop() {
    
    if(Serial.available() > 0){
    recv = Serial.read();
    pwmSpeed = analogRead(A4) / 4;
    switch(recv){
      case 's':
        Stop();
        break;
      case 'f':
        forward();
        break;
      case 'b':
        back();
        break;
      case 'r':
        right();
        break;
      case 'l':
        left();
        break;
    }
   Serial.println("Received input");
  }
}

void forward() {
  forward(motor1, motor2, pwmSpeed);
}

void back() {
  forward(motor1, motor2, -pwmSpeed);
}

void left() {
  motor1.drive(-pwmSpeed);
  motor2.drive(pwmSpeed);
}

void right() {
  motor1.drive(pwmSpeed);
  motor2.drive(-pwmSpeed);
}

void Stop() {
  brake(motor1, motor2);
}

Everything works well except the back() and right(), where motor2.drive() has a negative value (running backwards)
I have two of these drivers and i tried with both, and the problem is still there.
And when i switch the two motors, the one connected to A1 and A2 is still the motor which does not work
Can someone help me please