Coverlay mask

How do I add the COVERLAY_TOP mask layer created when building pads into my artwork (gerber) files? 

This is my first work with FLEX circuits,  is there something I'm doing completely wrong?   

Details:   The circuit is essentially 6 inch long FLEX cable with 2 components,  one plugs into a ZIF connector, the other is an array of surface mount pads used as electrodes when dipped into solution.  I built both ends as custom symbols .  The zif was easy , no problems there.   The electrodes will be gold plated surface mount pads.  In the pads editor I used the coverlay-top instead of the soldermask_top as a mask layer.   After placing both symbols I added a shape on the coverlay_top layer to mask the entire ZIF.   My problem is that, and not for the lack of trying, I cannot figure out how to add this coverlay_top mask layer to my gerber outputs.    In the  COLOR DIALOG there is a Rigid flex class in which I have enabled the Coverlay_top subclass , and by doing so I can generate the artwork that includes the shape I added on the ZIF.   I've gone into the cross section editor and added the flex layers but this has no effect either.    I'm about ready to change the mask layer to soldermask_top and create the artwork that way.   

MSC   10/11/22