There is absolutely no problem at all with the system - Xaver 400!!!!!! This is part of the systems operational method.
A short explanation: Since the system needs to detect any live object behind various kind of walls even when the object is not moving at all, it is necessary that the system will be stabilized with zero movement. In other words when moving the system it calibrates each time in order to get accurate results, if this process didn't occur we wouldn't be able to get an accurate acquisition and position of the target in matters of centimeters like we do today.
When accuracy is a factor re-calibration is critical!
Another aspect that makes the calibration critical, is the fact that walls aren't homogeneous, therefore when moving the system form one part of the wall to another, the system needs to calibrate itself to the new structure it is facing, even if it is the same wall, without this process we would face penetration problems, which we don't have thanks to the smart engineering that orders the system to re-calibrate itself automatically.
Think of it as a driver changing from his own privet car to another which is absolutely the same brand and model, when doing so if he won't adjust his seat he might not be able to drive it although the other car works just the same.
When accuracy and reliability is an decisive factor re-calibration is critical!