I am currently working with Asus Tech Support, it's been escalated to their Tier 2 people... spent almost 1 1/2hrs with the Chat Tech person trying to figure it out.
I was on 0223 BIOS, which I thought might be the problem, but I updated to the 0606, problem still persists and it's completely random. I had one boot where I literally changed nothing, the drive was there, I rebooted even though I changed nothing, which is annoying, and the drive was gone.
Troubleshooting included: trying a completely different drive in each slot, trying different drive in each slot (the one that was in M.2-2 always is the one that disappears the most, M.2-3 only disappears in certain circumstances). Tried resetting BIOS with Clear CMOS completely, because the BIOS actually completely bugged out and was unusable at one point when I was adjusting how tight my CPU AIO Block was mounted, the drives re-appeared, then I changed something and M.2-2 disappeared again. The drive in M.2-3 will only disappear once in a while, and usually only when I ENABLE the GPU+M.2 Storage setting, which SHOULD be ALLOWING both drives to show up, it does the OPPOSITE, and makes both of them not work or show up in BIOS.
It's also annoying that just having ONE drive installed in the M.2-3 drive slot, with nothing in M.2-2 STILL makes the GPU slot run in x8 mode - that was not the case on my previous board, I could have all 4 slots occupied & the GPU slot ran at a full x16.
If they can't offer me a solution quickly enough, I'm going to end up returning the board to Amazon - might try exchange first, but most likely it'll be for a refund, can't take the chance of it happening again with a new board & falling outside the return window.
I did completely reseat my CPU, as in I took the cooler off, cleaned both, took the CPU out completely and put it back in, made sure the ILM was on there good, and redid the CPU cooler mounting - my temperatures are a bit better this time, so I do think mounting pressure was a potential issue, but it's made no difference in terms of the drives appearing/disappearing (I was really hoping it was some bad contact on Pins or something, but I didn't see any damaged pins or any damage of any kind on the CPU).
This is so frustrating, because I love this board, other than this issue, but the primary reasons I bought it was it having 5 M.2 drive slots and 3 of them having the bigger heatsinks on them, as I use those drives for AI/General Rendering in addition to gaming... the heatsinks work great, but that don't matter if the drive is there sometimes & not there others, depending on the boot up.
On a lighter note, I did manage to get CL28 6200MHz on my RAM tested and at least 'stable enough for now' - those settings are another thing that frequently made the M.2-2 drive disappear, any time I messed with RAM speed beyond 6000MHz or FCLK above 2000MHz, it would disappear most of the time. And I'll prioritize running this 2x48GB kit at tighter timings at 6200MHz CL28 with 2067MHz FCLK over having the extra native M.2 slot compared to my previous board (X670E AORUS Master). I wanted out of the Gigabyte Ecosystem, looks like I may not be able to do that just yet.
