I have exactly same problem with EliteBook 830 G8 and USB-C Dock G5 and BIOS sp113061. Also tried to rollback bios and update bios over USB, etc... In update process it updates "Intel Converged Security and Management Engine Firmware v. 15.0.10.1447" about 15-20 min and reboot twice after that and starts windows. Some reason it is unable to update Thunderbolt retimer and USB-C controller firmware. I didn't find a solution to update those separately.
