In Hierarchies, Only Parent Records Are Displayed with Icon for Expanding Row

In a hierarchy, such as an account or campaign hierarchy, only parent records are displayed with an icon indicating that the row can be expanded to show children. Previously, rows for records at the end of a branch appeared to be expandable. This change applies to Lightning Experience only.
Available in: Lightning Experience
Available in: Group, Professional, Enterprise, Performance, Unlimited, and Developer Editions

Row for a record at the end of a branch in an account hierarchy