Wallet Hub Software Engineer, Backend interview questions

I applied on the website and got a response from one of the company's recruiter to complete a project that was poorly explained and was sent over in a text file. Spent almost a full day designing, writting and testing the code. I sent the code over to the recruiter and he said that they will get back to me in a week or two. After about 12 days he said that they did not want to move forward with me. I asked for specific feedback on why the decision was made and the answer was the solution is confidential!! I'm pretty sure they didn't even run the code. I wasted a full day and they don't even want to tell me why they didn't like my code. BE AWARE!