Invisible Technologies Forward Deployed Engineer interview questions

Started with a recruiter screen, then another call with a tech lead, then a call with a principal engineer and then one with one of their operations leaders. I passed all of them and then they flew me to be interviewed by their client which is a large private equity firm in NYC. Up to this point they had signaled I was good for the position and they were excited to work with me. They had told me the NYC conversation would be mostly about fit but it turned into a system design interview. Their customer did not want to hire me and therefore invisible did not hire me. Be advised that they have not refunded me for my trip to NYC even after months of back and forth.