Lucious guns Sustained Fire blessing not working with charged attacks

I was testing Lucious guns with “Sustained Fire” blessing in meat grinder, its seems not working with charged attacks. If that is intended, why that blessing even exists on those guns?

Steps to Reproduce:
Get Lucious gun with “Sustained Fire” and check charged attack dmg in meatgrinder

Player ID:
Steam ID vbybvfhrtn

Reproduction Rate:
Constant (100%)

Bump. I tried it myself today.
To my surprise it actually works with charged shots on helbores, making it a not bad blessing.
It does not work while aiming down sights. It only works while hip firing, with generous enough time window that fully charged shots can work. When you ads, not even tap firing regular shots benefit.