Model Item problem / Bug

I've got what sure seems like a but on how model items work. So i'm applying model item widgets to parts and sub-assemblies in my experience. I use the model items to control visibility and run code on a click event (when you touch the model item in 3D). Visibility works for both parts and sub-assemblies. But the click events only work on the parts. Clicking any part in the sub-assembly does not run the clickEvent code.

Please tell me there is a way to make this work for sub-assemblies so i don't have to create a separate model item for every part in a sub-assembly.