@manthan
I did a similar thing as you have done with the changes to x4x4x4x4 with the only difference is that I have the 4 slot carrier card. After seeing a similar post where @Hutch-45Drives gave suggestions, I went back and change the BIOS setting to AUTO and found the motherboard recognized it.
I used the cli commands that I posted here to confirm what was detected and the bus address assigned. I hope to make a follow up post once I receive the new NVMe sticks that I ordered for the carrier card (I purchased for my HL-15).