one idea that i will try tonight; there is a LOCK mode in the left side bar of camera settings, therefor: 1) place a white target iluminated 2) frame that target covering as much as you can the entire picture (viewing in the ST16) [covering the entire F.O.V of the camera will be the best] 3) select Auto WB 4) wait until you see that the camera has perform WB 5) without moving a hair, enable LOCK mode. And let see if the WB stay without change or shifts as you move arround and under diferent types of light surce (tungsten, led, daylight, fluorescent....
The "Kelvins" of your light type decided when WB must stay LOCKED and not change (exiting LOCK, i think, return the WB to Auto WB)