Just noticed that my fingers didn't write what my head was thinking!
Nearly flat, nearly level positions allow the auto-leveler to work fine. It's the more uneven scenarios that can cause it to fault. Which is certainly why your dealer can't make a fault occur while sitting in the repair shop bay!
We too have experienced the low voltage alarm a couple times. Randomly, it seems. I give the throttle pedal a little push-and-hold just before pressing the AUTO level button...