Anyone else seen stock available on singletrack bikes website, only to purchase and then receive an email three days later to be told its out of stock? Is this a frequent occurrence?

Nothing but good things to say about Singletrack Bikes personally. Only ordered once from them (some Park goodies), but they made it clear one of the items wasn’t in stock (even though I ordered it knowing that) and kept me updated as to progress and when the whole order would be shipped.

Would use them again.

Is this a frequent occurrence?

Yeh, with pretty much everyone
Seems google shopping won’t return a result unless you mark an item as in stock so there’s one reason
Another is that, if distributors offer/promise rapid delivery, a shop’d be daft to hold high stock levels so instead they might either show “in stock” or “available within 2-3 days” and order on demand