1) The device might be working in USB 2.0 mode when you short any of those lines to ground. Please check this.
2) The polarity inversion detection is an inbuilt feature. It cannot be disabled.
- Madhu Sudhan
we have disconnected the USB2.0 data line，we make sure it‘s working in usb3.0 mode。
Device can function in USB3.0 (SuperSpeed) mode even with one of the differential lines permanently connected to GND, but not reliably in noisy environments. Measuring impedance between GND and USB lines can be the simplest solution to your problem.
During the testing process on production line(FCT system),the target board and the test tools are powered on,it's hard to measure the impedance between gnd and USB3.0 data lines, if we want to measure the impedance ,we need ICT system .it's more complicate.