Distance Sensor 2nd Generation; distance will not change

I have 30, second-generation distance sensors. Now and then, one of the sensors is stuck at a distance and does not change. I am using a Gen 2 Brain and going into Sensors. I have tried powering off and back on. Plugging and replugging, and nothing seems to work consistently. Today I had a sensor "freeze at 7inches. I changed to MM, and it was still frozen. I then put in a sensor that I had marked as frozen on a different robot, and it worked!
Has anyone seen this issue?