Kumos Pete likes to ask me for the frequently, which fine. Except when I go to buy it from the Kumos NPC shop, it always shows as sold out. But no matter how many times I refresh the quest page, it still insists that it is in stock there. It's been doing it for a few days now, though I haven't had the same issue with any other items. And it's not that I bought it either, as it doesn't show up anywhere.

ETA: (I think this MIGHT have been fixed by https://kumos.subeta.net/changelog/5, I will report back there if it recurs.)

And tonight I discovered another item doing the same thing: Maybel keeps wanting it, same sold out in NPC shops

That's an ongoing issue. More and more shops and items are concerned.

I'm having the same problem