Walmart is huge and therefore has huge supply chain problems. I wouldn't be surprised if some of their distribution centers are well stocked and feeding their stors while others are tapped out. I don't know where the DC for your for Las Vegas is but wouldn't be surprised to learn that it's half way to Provo.
Walmart also have a pretty minimal commitment to hunting and shooting sports. They are also under a lot of political scrutiny. I'd expect them to come back last.
You're lucky. Walmarts around here don't even stock weapons or ammo - for obvious political reasons.
I know, I went to check out their prices on a 12 ga. Told the guy I wanted one for home defense. He smugly replied that Walmart does not sell defense weapons, only for hunting.
I didn't even bother with a reply, what's the use.