If Rays option works please update us..if not we had a similar case last year where there was an appstack copy operation from vSan to NFS and then vSan. It turned out to be default behavior on the copy to the NFS if im not mistaken but it came to be storage related after a test of a NON appstack .vmdk copy operation (Any .vmdk created in vCenter) produced the same issue.
If the same is true for you then i recommend opening a case with vSan for further troubleshooting on this one.
