So why did Prosper lose those 66 cases if they had top notch legal team and actually owned the loans?
Because they're a bunch of fuck-ups. In many cases they didn't get the paperwork right, even after the courts told them what they needed to do. IIRC, they often didn't get the defendants served, if they did get them served they didn't file proofs of service with the court, if they did file POSs, they failed to move for default judgments, if they did move for default judgments they fucked up the paperwork, etc., etc., etc. Then eventually Prosper simply started dismissing the cases because it took the position that its SEC "silent period" prevented it from responding to court requests, which is absurd.