Under desk treadmill step count

I am currently using a Venu 2 Plus watch, however, the watch doesn't register any steps when I am walking on my under desk treadmill coz my arms are resting on the desk. If I use the HRM Pro Plus with my watch - 1) Will it record the steps on the under desk treadmill even when my hands are resting on the table 2) Would I need to start an activity like walk/run to register the steps? 3) If yes, would those steps get added to my daily step count?