Availability Report and Assemblies

I am trying to figure out how the Availability report chooses whether to include the children of an assembly. I have tried looking at the Engineering Workbench fields for ‘pull as assembly’, ‘view as assembly’, etc. but those do not see to have an effect. And it doesn’t seem to be related to it being a phantom or not.

Within one unit, some assemblies show their children while others do not. If I take the part # of an assembly that does not show it’s children, and I run it as the top level part for the report, I will get it’s children without any trouble.

Has anyone else run into this issue?
Is there some other driver for this functionality that I am missing?