I have just completed dungeon 1 of battlefield 1 and found nothing on the bottom level except for 4 or 5 rooms. Did I miss a hidden door or lever? Also, I have yet to come across any of the BF1 quest mobs; are they in dungeon 2 or dungeon 3 which I am not able to open yet?
The last level of a dungeon might contain nothing. When you collect quests from the BF merchants, you do not know where these quests will be solved, and the game generates the monsters/items, so some BF dungeons may have empty basements...