Valid submissions made from SESC on Exchange 2013 are not reflected on the SMG submission detail page.
The X-Brightmail tracker is being stripped from the submission. Without the X-Brightmail tracker, the submission will not be considered for Customer Specific Rules.
Exchange 2013 has a feature called Header Firewall which removes X-headers from messages and attachments. This feature must be configured to no longer strip the X-brightmail trackers from messages in order for Customer Specific rules to be created.
See: https://technet.microsoft.com/en-us/library/bb232136%28v=exchg.150%29.aspx for details on the configuration of the Header Firewall feature.