Kinda reminds me of when I was trying to purchase a GTX 1070, or 1080Ti, honestly can't recall which one I was going for, back in the crypto-craze. Nvidia would always sell them at MSRP.
If I recall, I went through 3 times where it was in the cart, then by the time I got to click to actually purchase, it was gone.
And all the other models would be gone, too. Weirdly, the 3rd time, I stopped, talked to a colleague about it for a minute or two, then noted that the GTX 1080 was still in stock. After a brief debate for a minute or two ("Nah, that's not really what I was going for") I gave it a try anyway, and lo and behold, I somehow, miraculously, got it.
It was a weird experience. Somewhat akin to release-date, but honestly, I don't quite understand the demand, as I doubt crypto-miners are part of this. Or maybe the scalper-bots are playing the role crypto-miners used to play.