Ah-ha. I have found the issue. We wear our BB's on our left hip. The case is designed to have the BB with the top facing to the right as you are looking at the clasp on the case. If you insert the BB 180 degrees in the opposite direction with the top facing to the left the sleeper magnet does not work. The BB stays on.

As a design note, Fortte should have placed magnets on both sides.