The original model has a gap between the clip fingers and the back panel of the clip.
As a result of the fingers not being attached, they break off the instant a rope light is pushed between the fingers.
You can see the gap if you load the .STL file into slicer software or Blender and zoom into the area.
I edited the .STL file in Blender to extrude the fingers so they merged into the clip back panel.
It fixed the problem and made the clip model usable.
Enjoy!