PC struggling to run XMP despite supporting the ram model

Good evening all,

So I'm reaching out to you all because I'm seriously confused by my system. On paper, everything is fine, good CPU, good (supported) memory *1, all motherboard slots for the PSU are plugged to support the hardware with the necessary juice, and yet my memory can't even boot when I set the profile to XMP 1, 2; even when I switch slots from A1B1 to A2B2… Nothing. I'm tired of doing all these returns and playing around with my system. Is this a known issue with Intel?

For further context, my processor is an i5 13600KF and my motherboard is an Asus Z790 Hero. (Yes it sounds overkill but down the line, I'll get a secondhand i9. The i5 is a good upgrade from my previous system and meets my needs as is)

If you guys need any other info from me, I'm happy to cooperate to find a solution to my problem. If any of y'all tell me to manually overclock, could y'all provide a neat written/video guide because I've tried to make sense of it and none of it works :/

Cheers

*1: https://rog.asus.com/motherboards/rog-maximus/rog-maximus-z790-hero-model/helpdesk_qvl_memory/ ( Page 8 – F5-6400J3239G16GA2-TZ5RK )