Exporting to Web Format not using transparency when including feature layers

staffordt

exporting to web format - Worldwind.   I generated contour lines using GM20.1 as a layer.  If the contour lines are active when I do an export, the tiles are not transparent outside of the edge bounds.   By turning off the feature layer, the export looks correct.  

I understand that this is probably not a heavy-use feature for GM, but it has been a useful tool for generating tilesets for our WorldWind based application.

To reproduce it, you can use any online or local data layer, along with one feature layer containing one or more features.  I attached the export options I used.

I appreciate any help in this as it is preventing me to including contours in out exported maps.

Thanks