Volume (CA) Software Engineer interview questions

I was asked to solve a take home exercise. Build a simple microservice. Requirements where a bit confusing, but nevertheless got to solve everything with a good level of quality. I was told that the work was of very good quality and didn't have any feedback for me. Nevertheless, my application was rejected without any explanation on why. Tried to inquire a bit more, but got ignored. Invested a lot of time on that exercise, I think should have recieved at least some minor feedback.