1st C apron attachment peculiarity?

[Tarbicus]

There's a few other soldiers depicted with aprons shown 'vertical' to the slant of the actual belt. Most of Tiberio/Claudian date and show the terminals all matching horizontally, but where the apron attaches to the belt, it's actually at an angle.

I'm not talking about the angle. Where does the apron attach? Both buckles are in the way, and the only means of attachment to either of the belts would be if the apron was split into two. Hence I'm asking if the apron is attached to the waistband.