QVL means someone actually tested the modules on that board. They can't just copy and paste because there are differences between the boards.
Why certain kits were validated on one but not the other? Could be a timing thing if the release dates of the two boards didn't line up with when the kits were received from the memory manufacturer. Could be they were actually tested but didn't pass for some reason on the Apex.
It's almost certain the list will grow over time. DDR5 is new so things are going to change as the companies figure out how to make it work better and broaden compatibility.
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Apex is one of the best Boards for running RAM......at this point I wouldnt pay much attention to the minimal list. Better off to reach out on Forums and you'll get a good idea of what we're all using 😉