If you have completed a trade with someone who looked like one of our bots, but you didn't receive any items in exchange, you most likely have been scammed.
But how could this happen? I have the mobile authenticator.
You have most likely entered your Steam Login information on a fake Steam Login page and the hackers have gained access to your Steam Account. They have created a Steam API Key, so they can access your Account without having to enter the Steam Guard Code every time.
They have declined the offer sent by our bots and sent you a similar looking offer, with no items being given to you and they accepted it automatically.
You confirmed the offer on your mobile authenticator without knowing you wouldn't receive any items.
You have lost your items to a scammer and it is unlikely you will get them back.
Now that you understood what has happened, we suggest you clicking here to find out how to make your Steam Account secure again.
We also recommend you reporting the scammer on Steam as seen in the picture below.
You can also report the scammer on SteamRep afterwards, to warn other people from trading with them.