Approve Status sometimes 'Not Approved'

Approve Status sometimes 'Not Approved'

Hi
 
I am fairly new to using Desktop Central and I am seeing something that is potentially a bit odd.
 
Our Desktop Central is set to automatically scan, download and apply updates, however a few machines seem to need updates which are marked as having an approve status of 'Not Approved' - what causes these to appear as not approved and why do they need to be pushed manually.

                  New to ADSelfService Plus?