A couple of people have noticed that on occasion when they apply the Automatic Approvals for matches above a certain score, a few of the potential matches don’t get approved, and remain categorised as “Not set”. This behaviour only applies to Best Match projects, and is actually quite rare.
This happens because a match has already been approved for your Source List using different criteria, but the approved match is not shown because it is outside of the current matching criteria that you have selected.
I hope this helps, as always your comments are welcome.

