In T4.4 versions of the game, any artifacts that have not been captured by the players and are still held by the Natars 30 days after the artifacts spawn will become active. While something is tickling my brain about this also happening in earlier versions, what is unusual and confusing is that the treasure chamber does not show the Natar artifacts as active, even though they are.

TechSupport and the developers are aware of this and are working on a fix, but no word on when a patch that contains the fix will be released.