Manufacturer makes a motherboard model, makes the manual and tests the "final version" of the motherboard with a bunch of memory modules they have in the factory THAT DAY.
The test day could be a week or more BEFORE the motherboards actually arrive in stores for you to buy.
Some manufacturers will continue to validate various models of memories and update those QVL lists from time to time, but most often after 1-2 updates, they don't bother updating the list anymore. So it wouldn't be surprising that a particular memory stick model which is put on sale AFTER the motherboard was already on sale, will not appear in those QVL lists.
Those lists are INFORMATIVE .. they don't contain HUNDREDS of different memory chips from maybe 4-6 major manufacturers of DDR4 memory chips (micron, samsung, hynix, others) .
And another thing.
AMD licensed the DDR4 memory controller and they maybe made some tweaks at it but at least initially, the Ryzen processors only supported to 100% a limited number of memory chips - some memory chips were working but not at the frequencies and timings they were designed for because inside the cpu a lot of things were hardcoded to some strict default values. So, it's possible these chips didn't show up in those QVL lists when they made the lists.
.
Since the release of the processors, AMD has released multiple updates for the microcode (the software inside the processor) which increases memory compatibility and now a lot of those memory chips are supported 100% and work fine. If you update the bios on the motherboard, the microcode in the cpu is also updated.
You probably won't see updated QVL lists with memory modules that now are 100% working, after updating the microcode in the cpu.
