Dependency tracker seems to not track full names of system resources. For example with the following stored procedure like:
CREATE PROC TEST
SELECT * from sys.extended_properties
produces an unresolved internal referernce for 'extended_properties'. This happens even if "Add objects selected objects use" is checked. It's acting like the store procedure it refering to a table that has not yet been created.
It would be more useful if it at least produced the full name 'sys.extended_properties' and probably should use a table icon to show it with a note on the icon that this is a system resource.
Drilling into all system resources would unecessarily clutter up the diagram, but at least showing the first level of reference where they are used would be a help.