until you get an OS installed and all that i would keep xmp disabled...
but other than that, i assume you do not have another m.2 drive to test the slot with right? if you do then put in another one to see if that one shows up
if you dont, the safe bet could be to just return the motherboard and get another one, or same with the ssd..
tbh its hard to see which is the issue when you dont have other parts to test with