I have the same issue before and was able to submit a sample last month, an excuatable file (recycle.exe) to McAfee Labs and confirmed that it can be detected by the 5943 dat.
It executes then replicates itself as "Actual foldernames.exe" with a folder icon and hides the actual folders. I higly suggest to send a zip sample with a password "infected" without " to Virus_Research@avertlabs.com
I did it I still waiting for their feedback.
Have you called support to log a service request for this?
Also as a Gold Support customer you have access to our corporate submission tool:
This is the preferred method for McAfee Labs to receive submissions from Platinum and Gold Customers. When you use this method we can process and respond to samples more rapidly. You’ll find instructions for using the McAfee ServicePortal/Platinum Portal under McAfee KnowledgeBase ID KB68030.
Hope this helps!