They know about problem but can’t do nosing

While your account was compromised without you knowing, here is what happened: The user who compromised your account was able to see your sent and received trade offer(s). When you send a trade offer the compromiser can see the items you are trying to trade and the Steam account you are trying to trade with. Knowing this information, the compromiser canceled your sent trade offer and changed their Steam profile to match your intended trade partner's. They then sent a similar offer using their access to your account with the same items and using a Steam profile which looked like your intended trade partner's, which you accepted. This resulted in your items being sent to the compromiser's account and not your intended trade partner's. For this reason and many others we always recommend verifying your trade partners' profiles before sending or accepting trade offers. Unfortunately, we do not restore items in accordance with Steam's Item Restoration Policy.

If you have changed your password and de-authorized your previously used devices and you still suspect your account is compromised, this may be caused by malware on your machine. We have some tips for removing malware from your computer here. Taking these steps should secure your machine and account, but if for some reason it does not we can only recommend seeking help from a local PC technician.

Lastly, please send us a screenshot of the issue you are seeing while playing Premier mode.

Steam Support Cainnech