Unable to move localAnchorB body in RevoluteJoint if Vector2(0,0)

Question

In the following RevoluteJoint, if I set localAnchorB to Vector2(0,0) Then I am unable to drag the Component with MouseJoint.

But If I set it to just Vector2(0,0.1) I can start to drag it around the point.
And setting the motor also works with Vector2(0,0).

Note: BaseBox is just a BodyComponent with a MouseJoint, so I can drag around and reuse. I am not including the MouseJoint for simplicity and the fact it works setting localAnchorB to Vector2(0,0.1).

class Box extends BaseBox {
  BaseBox? boxToAnchor;
  Box(position, paint, [this.boxToAnchor]) : super(position, paint);

  @override
  Body createBody() {
    super.createBody();

    if (this.boxToAnchor != null) {

      this.boxToAnchor!.priority = 1;
      priority = 0;
      body.setType(BodyType.kinematic);

      final revoluteJointDef = RevoluteJointDef();
      revoluteJointDef.bodyA = body;
      revoluteJointDef.bodyB = this.boxToAnchor!.body;

      revoluteJointDef.localAnchorA.setFrom(Vector2(2, -2));
      revoluteJointDef.localAnchorB.setFrom(Vector2(0, 0)); // No problem with Vector2(0,0.1)

      /*    revoluteJointDef.enableMotor = true;
            revoluteJointDef.motorSpeed = 2;
            revoluteJointDef.maxMotorTorque = 1000;
      */    

      RevoluteJoint joint = RevoluteJoint(revoluteJointDef);
      world.createJoint(joint);
    }

    return body;
  }
}

Example 1

With revoluteJointDef.localAnchorB.setFrom(Vector2(0, 0));

Example 2

And with revoluteJointDef.localAnchorB.setFrom(Vector2(0, 0.1));

The closer Vector2(0, 0.1) gets to Vector2(0, 0) the more responsive.

Example 3

And using motor with revoluteJointDef.localAnchorB.setFrom(Vector2(0, 0));