Relax. Don't call. Nothing "strange" or unusual going on at all. This is typical behavior. Sheesh.

On Chase business cards (all of them, IIRC), new charges first appear as pending, then they often drop off and disappear completely for a couple days before they post. Yeah, it's weird and a little annoying if you're trying to closely keep track of things, but just climb down from the ledge, relax, and give it a couple days. The charge will show up soon enough and you will not have to worry about any "free" gift cards.

Don't freak out over nothing. And DON'T CALL.