OC1 Light goes off when accessing Dive menu

[BjFaeTorphins]

If i switch the back-light when in the normal watch mode time display screen then press the M button for more than 2 secs to access the Dive menu the back-light goes out and won't switch back on.

Is this as it should be and why?

 

[Mr. Fix]

On my unit, it switches back on when I get to the Dive Menu.