I am using Restrained Life viewer, and I am locked. My HUD is undetachable, but why are my cuffs / gag detachable?

If you are using any of the following:

Signature Gag v3.20
Signature Cuff v1.045 or v1.046

There is a bug which still makes the gag / cuffs detachable even though you are locked and wearing the Restrained Life viewer.

To fix, upgrade to the latest version.