Motor won't move forward, but will move backwards

We are using the following code for just a tank drive setup using omni wheels. However, this code is not working, or something is wrong with the motors, we are not quite sure. When we run it in the debugger, all of the right motors will go forwards and backwards. But the left motors, will only go backwards, and they are in separate ports, so it isn’t a y-splitter issue. They will not go forwards no matter what positive value you use. Has anyone else had this issue? Or suggestions on how to fix it?

motor[frontRightDrive] = vexRT[Ch2];									
	motor[backRightDrive]  = vexRT[Ch2];
	motor[frontLeftDrive] = vexRT[Ch3];
	motor[backLeftDrive] = vexRT[Ch3];

Also, when we run code that doesn’t depend on a channel, and have the left side go backwards, it goes backwards, but when we have it go forward, it doesn’t move at all. So it isn’t a controller issue either

It feels like a hardware issue to me, check the motors will respond to fixed values and also make sure the joystick is working by using the joystick debug window or by saving the joystick values into a global variable and checking those in the debugger.