Ram Overclock (XMP) doesn't work properly

Any memory QVL is basically unreliable (for all brands), As far as I know, only Samsung and Crucial are true manufacturers, the rest are assemblers, who buy chips from Samsung, Micron, Hynix, Nanya, Elpida Spectek anbd other chip manufaturers.
Since introduction of DDR4 there is a shortage of chips, so maybe ASRock test with a kit with 512MB Hynix chips, abd a week later the same kit contains 1GB chips of a different brand.
Kingston is also an assembler, and this would not be an issue, if manufacturers would not keep reusing the same partnumber, it's a silicon lottery
The memory controllwr is integrated in the CPU and runs optimal at 2667MHz,
https://www.amd.com/en/product/9121
Probably lots of people will comment, but the overal performance of the complete system, will not increase above 2666MHz, only a synthetic memory benchmark will show an increase
When you still want to overclock, google for Ryzen DRAM Calculator, and watch the youtube tutorials, they are quite helpful.
The general idea is to use a freeware tool like Thaipoon burner, to export the content of the memories SPD chip as an HTML file.
Import this HTML file in Ryzen DRAM Calculator, who will find optimal values.
When you have a FAT formatted USB stick, you can make BIOS screenshots with f12, and use these as a guide to find the apropriate values.