Not a bug, that worked exactly as it's meant to.
In the Hobbit Draft Game, there are no special rules about The One Ring; it is merely an Artifact that has a particular name, no more special than
Gandalf's Staff or Anduril or anything. A card with 0 cost was revealed, and so the only free peoples card with a twilight cost of 0 was discarded automatically; if you had had 2 different cards of cost 0 then you would have chosen, but Gemp did it for you since you only had 1 valid choice.