Incorrect mandatory element count for units

Hi.
The problem is that when I add a mandatory element and update the unit, and then again add a mandatory element and update the unit, the count displayed in the units page does not change (stays 1). I have made a video to show you the problem: https://www.youtube.com/watch?v=N-sij5PIKfs
I have tested this on 3 different wordpress installations (one of them had all plugins disabled).
Thanks.