by roboraygun
Welcome Orion to bbg!I have the 2nd edition, and in my copy of the rules it says that in haunts where monsters are allowed to carry items they do drop them when they are stunned, so I think in this case the secrets of the traitor tome got you :/.
Also tho as mentioned by then other poster, I wasn't sure if you were saying your group was using the monsters to "explore" (walk around the already opened rooms of the house) or you meant "explore" explore (flip over new rooms), but if its the latter, monsters can't flip over new tiles exploring unless its something haunt specific (which in my copy #14 doesnt say they can).
Hope that helps!
-E