Troubleshooting
Why does a pure black (<0, 0, 0>) PBR tint turn white?
Pure black is a known limitation of PBR material tinting; use a near-black shade instead.
Why it happens
This is a platform limitation of PBR (GLTF) materials.
When the product toggles part visibility (for example when locking, sealing, or hiding parts), it has to read the material color and write it back. On read, pure black <0, 0, 0> is indistinguishable from "no color set", so it is written back as the default: white.
Workaround
Set the color to a near-black shade such as <0.05, 0.05, 0.05> or <0.1, 0.1, 0.1>. It looks virtually identical and does not trigger this limitation.
Affected products include The Purrfect Chastity Belt and The Forbidden Chastity Belt.