Latitude 5520 Bitlocker Docking Station external keyboard not working

Until Latitude 5510 the how-to (BIOS, Postboot, Fastboot, Thorough) works fine.

Since the new BIOS on Latitude 5520 configuring BIOS the same way, this time in Pre-boot section, doesn't work for us.

Drivers, Firmware, BIOS are as new as Dell Connect Update is able to install.