Show total checkboxes in "Summary on parent item"

So if you add a checkbox to an item, you can see a neat summary of all checkbox for the group at the bottom:

But I like to use checkboxes for subitems, and then use the “Show Summary on Parent Item” function.
But then I can’t seem to find a way to see the amount of checkboxes for the entire group:

This appears to be a problem with all “Show Summary on Parent Item” cases. But I’m not sure if I’m missing something.