The holster style (nikana right shoulder holster) is not working on my nikana zaw.

[Metamic]

Every time i equip it reverts back to the default holster whenever i leave my arsenal. No matter what i do to fix to it, it doesn't work restarted the game still doesn't work, reinstalled the game still doesn't work. and it seems I'm not the only one who has the same glitch please help out if you can.