I did all the steps described in that post. However, C8E’s BIOS for Thunderbolt security has only two options, which are “No Security” and “USB4 Only”. After re-installing Windows 11 build 22000(21H2) twice, the PCIe tunneling is still shown as disabled. BIOS revision is 0801 (latest as of now).
After speaking to ASUS support team and going to one of there services centre they didn’t have any answers at all and confirmed these nothing wrong with my board they even tried the thunderbolt ports on a brand new board they had in stock starting to think that it has not been enabled fully