Comment 8 for bug 1878602

I'm not aware of any known issue like this.
Is there any USB3 device connected at all?

The only sign of a connected device is that one time CAS bit is set.

device never reaches enables state (no successful link training), no error,
not going to invalid or compliance state either.
Just stays in disabled/Disconnected, as if no device is connected.

Driver tries everything to enable the device, several resets, warm reset, turns port power
off/on, but no reaction.

(CAS -Cold Attach Status is set when xHC can't advance the link to the enabled U0 state due
to itself being in D3, or because its clocks are not running.)