Santo Domingo was the first area that I get the achievement for complete all side and NCPD, I finish before even talk with Goro at the dinner, very early.
I do have a problem with one particular NCPD mission, the location it on the image, if you go before do it other NCPD/Side quest (don't know what exact) the area its empty you can get the shard, read, and the quest disappears and you don't get the location of the stash.
So in my case, I reload and wait until the quest is actually active.
In your case may not be practical, so try to go to the place and see if have three enemies there, read the shard, it is about a guy that finds biotecnica case, and look for a blue container close by, open the container and loot, see if something happening.