E-M1X bird tracking and shutter half-press

Just bought an E-M1X. Tried using C-AF-Tr with bird recognition and had ok results but had some confusion. All the tips and advice online suggest that you need to half-press shutter for the camera to begin locating birds, drawing white rectangles. But when I invoked these settings the camera starts to draw white rectangles immediately and continuously before I touch the shutter button. It seems to be always on and eats battery. Have I got some other setting wrong?