Be sure you have inventory space as when you use a map pack it places individual area maps into your inventory. These are like the Treasure maps from Skyrim, shows a drawing of a location.
There might be a glitch causing you to be unable to dig up the treasure. Maybe try clearing your cache, then again it might get fixed in a future patch. There are so many things that need a patch in this game.
go to collections, that will move them to inventory under containers or sompthin like that, then open them tere and that will put them in another cat at the bottom of inventory, maybe consumables, I cant remember but its convoluted