SoM not deleting computers that have been removed from AD OU's

SoM not deleting computers that have been removed from AD OU's

We have two OU's that sync with DC. We moved 131 computers to our disabled OU, which has no ties to DC. 
We forced an AD sync this morning, then the normal AD sync happens every afternoon at 1pm eastern.

I received 14 emails after this. Of these 14 emails, 4 of them state the computer was deleted from DC. The remaining 10 states the computer hasn't been in contact for "X" days.

Our computer count in SoM only dropped a couple of machines.
According to the DC Admin Guide, on pg 51,

  1. - Enable the checkbox to Delete Inactive Computers 
  2. Specify the action that needs to be performed when a new computer is removed from the Active Directory or it has been inactive for a long time; Whether to remove the computer from the SoM automatically and notify me or to just notify me. 

Our settings in DC are:


Is there a reason these computers did not delete from SoM? Do we have to manually delete them from SoM? If so, what's the purpose of having an option to auto delete from SoM if the computers are deleted from AD?

EDIT:
I noted I can pull a report from the Disable OU. All of the machines are there. So i am going to assume that even though we removed them to a non-sync'd OU, they won't delete in SoM until they are physically deleted in AD?

EDIT 2:
I don't see a report for "Recently Deleted Computers." Can we get a query for that?