You may have noticed that the Usercertificate attribute of O365 contacts are not available in the QC Synch Engine, even after extending the connector’s attributes:
How to extend the Quick Connect connector schema (71853)
This is a product defect (TF00684277).
This will be fixed on a future release of the product. If you require this immediately corrected, please contact support for a hotfix referencing the defect ID TF00684277.