Sheet View in a Titleblock Family

Open a Titleblock family and then double click on the schedule in the project browser to open it in a separate view. With the schedule as the current view, close all the other active views. Notice that the view with the titlebock itself closes and now there’s no way to open it again, since it’s not listed in the Project Browser.

The subtle bit is that the view is still there in the project browser, it's just hiding under Sheets instead of Views where we'd expect to find it. It's that even more subtle dash listed beneath Sheets.