I cannot see why it should make a difference - but try something! When I first acquired my Kamiq - my first automatic - I too noticed that the stop-start rarely operated, although it didn't particularly worry me. However, when one day I changed my body position whilst stationary and unintentionally pressed harder on the brake pedal, the engine suddenly stopped! After experimenting a few times, it seemed to be the case that if you only applied light pressure that nevertheless was enough to hold the car stationary the stop-start would be inoperative, but apply more pressure and it came into play.
It does not make sense to me, plus it is a pain in the arse pressing so hard that it is uncomfortable, so most of the time I don't bother.