Cimpress Senior Full Stack Software Engineer - US Remote interview questions

Had 4 interview. Did a design interview where I had to determine how many shampoo bottles you would need to order all hotel rooms in the U.S. Did another design interview where I designed a REST interface. Did a technical interview over C# and ASP.NET topics. I received positive feedback in each interview round. I thought I was getting an offer. No offer, and no explanation as to why I was passed on. Waste of time.