Ok. So I starting looking in various locations.

I am not exactly sure where the "saved game" files are located in your game running through steam.

C:\Users\YOUR_USER_NAME\Documents\Endless Space 2\Save Files

Map shared with the riftborn and nothing was revealed.

New Empire.zip

Ok, I have done some different loads.

I am thinking when map sharing is picked as an option; it should appear as a contribution in both parties window.

When I placed the map sharing in both party's diplomancy window the map then updated.

Ya I reloaded the menu under different options.  I think there was a misunderstanding on my part when the option is selected to map share.

I thought "Map Sharing" implies that we each show each other our revealed maps; but this isn't the case (as only one party can reveal).  Perhaps the term should be called something more like "Reveal Known Galaxy"; that way the implied reference to "sharing" wouldn't lead to confusion.