TUSB1002A: USB 3.0 loopback test fail

Dear Team,

      My customer is designing the type C USB 3.0 host with TUSB1002A and HD3SS3220.

      The simplified block diagram is depicted below.

       They find when connecting to a USB 3.0 loopback plug and doing the data transfer speed test, the speed is only at USB2.0.

       if bypass TUSB1002A, the loopback test is pass and the speed is up to USB 3.0.

       But if replacing the loopback plug with a USB 3.0 hard drive, the data transfer speed can be up to USB 3.0 with TUSB1002A and HD3SS3220.

Would you kindly advise what we could try?

Thanks

Sincerely,

Edward