Why Doesn't the Dependent Document (Drawing) Show Under the Assembly in ECTR?

Hello, ECTR experts:

We have a strange issue for some of our recent assembly documents in ECTR. There is a dependent drawing document created from the assembly, but it's not showing up under the assembly document's structure tree. What's supposed to show up is another tree node "Dependent Documents." Does anyone know why this might be? These are all created in SolidWorks, by the way.

Kind regards,

Elna Hantalasevic