Here is CPU support list along with required bios for ASUS ROG Maximus XI Formula.
https://www.asus.com/us/Motherboards/ROG-MAXIMUS-XI-FORMULA/HelpDesk_CPU/
Code 00 means "Not Used" according to manual. I don't know what it means.
i9-9900K requires bios version 1602. I don't know what bios version is on ASUS ROG Maximus XI Formula.
What can you try ASUS ROG ? I think you need to buy a cheap 8th or 9th gen CPU (that is released earlier than 9900K) to put in to test the motherboard. If it works, then you need to update the bios to version 1602. After bios is updated, put in 9900K then it should work. You could take it to the local computer shop to test and update bios.
If you can, return both of them and get 10th gen CPU and new motherboard socket 1200 if you wants to stay with Intel. 10th gen i7-10700K (8c/16t) is equal or slightly better than i9-9900K; the price maybe cheaper also. i9-10900K or i9-10850K is 10c/20t.