This article describes autosizing and how to avoid issues.

Autosizing is how an IntelliTouch Surface Wave controller identifies the screen size it's connected to. When powered on, the controller sends a high-frequency burst to the screen’s transmit transducers. The receive transducers return the signal, and the length of the returned burst tells the controller the screen size—longer bursts indicate larger screens.

It's critical that the screen is not being touched during power-up. Any touch can disrupt the autosizing process.

To fix autosizing issues:
Unplug the monitor’s power cable for 30 seconds, then reconnect it. This resets the touch controller and re-initiates the autosizing process.