BrowserStack Lead Product Designer interview questions

I was referred for this role. First round was with the recruiter; she shared details about the role and expectations with me. The second round was with a panel of 2 designers (a manager and a lead). This was focused on my portfolio. Good vibe and they asked good questions. For the next round I was given a take-home assignment. It was a complex problem statement which was related to their product. Since I had some free time I decided to go ahead with it. It involved doing user research and building a proper solution. They had assigned a design manager to help with the assignment (basically give some feedback). I spend a week working on it and shared my solution with the team. After two weeks I got a response that I have been put on hold. In hindsight it feels like they got free work from me. They didn't even give me the opportunity to present my solution. That's the least you can do if you're giving take home assignments.