This enchantment, when applied to either this mod's bow or crossbow, gives the weapon a zoom-in capability and a crosshair reticle similar to a scope when drawing the bow/aiming. When RPG HUD is installed, the area of the screen this effect takes up, which is all of it except the outer layer is completely blacked out.

So there is a giant black rectangle onscreen? Sounds like an alpha problem. My mod should reset the alpha to it's original state after each edit though. I'll investigate this further once I have the time to do so.