The most likely reason is that somebody opened up IR LED part and fiddled the Zoom lens before. Then the actual location of step motor in zoom lens and where the software thinks the step motor is are different, and the difference make one push malfunction.

To reset the Zoom lens,

1) Press “Near” button on controller in PTZ mode on a NVR screen so that the Zoom lens can get as wide as it can get.

2) Press One Push, then it will find a right focus.