Possibly scammed? Most likely by a hi-jacked account?

Not honestly too sure what I should do. I've been scammed it seems, but by what appears to be a hi-jacked account. I've verified that I traded with the correct account. If you check my trades, you'll see that I've been trying to trade games for the cards people idle from them.

This person had nothing but positive rep, so I trusted them with all 11 games at once. It's been over 24-hours since then, the games are not active on their account, and they've been out of communication, so I messaged them about it. They removed and blocked me without saying a word. :c

What should I do in cases like this? I don't have any kind of chat logs (Any way to retrieve these?) so I can't exactly file a SteamRep report. Should I leave them negative feedback? I wouldn't feel right doing this since I feel like their account has been hi-jacked... What do you guys think I should do?

Of course, as usual, I verified that I was trading with the correct account, and I was, which is honestly why I'm so surprised this happened.