The Heartbreaker Kneepads are still missing the appearance slot, and the dye slot is still transposed off-screen.
One of the original threads from six months ago, currently found in General Discussion:
https://discussions.ubisoft.com/topic/157548/important-heartbreaker-appearance-mod-off-screen-issue
Moreover, as was the case with the Umbra Initiative Gear Set and Brazos de Arcabuz Brand Set, the dye slots on the Heartbreaker Gear Set have no functionality.
This persistent issue has no acknowledgement in The Division 2 Known Issues | Trello: (https://trello.com/b/F2RU9ia9/the-division-2-known-issues).
Please fix for the next update.