Gesture backlight not working on activity

When I have both gesture backlighting set to 'on' for both the watch and during activity, the backlight does in fact show when I lift my arm up etc; when in watch mode and during an activity. However, when I set the backlight to off on watch mode yet still on during activity, the backlight gesture doesn't show at all during an activity.

Settings > System > Backlight > During Activity > Gesture ON
Settings > System > Backlight > Watch Mode > Gesture ON

= Wrist turn backlight comes on with gesture in both activity and in watch mode

Settings > System > Backlight > During Activity > Gesture ON
Settings > System > Backlight > Watch Mode > Gesture OFF

= Wrist turn backlight doesn't come on in either activity or watch mode.

:confused: