Currently, the missing submission policy only applies to "online" assignment types.  Assignments of type "No Submission" and "On Paper" are ignored by this policy.

It would be great if this policy worked on all assignment types across the board.

What's the use case?

As currently implemented, the "missing submissions" option does not state that it only works on certain assignment types. Users will look at this, and assume that it applies to all assignment types.  When it comes to final grade calculations, this will then cause additional headaches.

Why is this important?

When syncing grades to SIS, and possibly for other grade calculations, it's important to have the desired value listed in the gradebook for missing assignments.  Using the "Default Grade" option on a per assignment basis is not intuitive nor streamlined for a Teacher.  Since Canvas determined that the new gradebook intentionally does not support the "Treat Ungraded Items as 0" option, teachers have no way to mimic this behavior with the new gradebook and the missing submissions policy.

See: https://community.canvaslms.com/message/141188-re-new-gradebook-treat-ungraded-as-zero