Item Card - Connected Boards widget - View Subitems

I would like to be able to open the Item Card of a pulse which has connected items, and view the subitems of those connected items.

My use case is that I have a High Level Projects board. That board uses Subitems for the milestones of the project: kickoff, design complete, released for tooling, samples ready, mass production, that sort of stuff. Each milestone has things like target date, actual date, status updates etc.; it works well to have them as subitems, and they show up on the Gantt chart nicely. Then I have other boards which reference this project list with the Connected Boards column. I want to be able to be on these other boards, open an item card which has a connected project, and be able to see the subitems (milestones) of the connected project. It is so close to being able to work because the Item Card view has a Connected Boards widget, where you get a table view of the connected item; however the subitems column is greyed out and it says “This column is not supported”.

You also cannot see the subitems from the popup item card of the connected item. It will just show the number of subitems that are there, but you cannot view the content of the subitems.