Why is the match rate for Ad Audience in Marketing cloud is nearly half of the match rate at Facebook Ad Manager while the same list of customers are being used and email add and mobile no are the fields for Matching?
Advertising Studio does not use the same logic as Facebook for matching. We are held to different standards due to the way Facebook works and has specified they will process our data. However, this doesn't mean that there isn't something awry considering what you've described.
I would contact Technical Support to see what can be found out (there may need to be communication between us and Facebook to touch on this). I would recommend getting a case going via the Help and Training portal for an easier process -- include screenshots as well as the account number, and names of audiences. Additionally, to expedite review provide impersonation access for Support as well.
