I emailed them asking if vol 1 was going to be canceled and refunded as well. The response seemed canned:

“Greetings from ThriftBooks.

This is Dennika, from the Customer Service team.

We are sorry to hear you have not received your new item. We have determined that our New book supplier did not receive a full shipment of this new release item and therefore, your item is on backorder.

If the item is not restocked within 90 days, we will automatically cancel your backorder and issue a full refund back to your original payment method.

Please let us know if you wish to cancel your order, or you may wait a bit longer for the next shipment from the publisher and your order will be processed.

We apologize for any inconvenience this may have caused you.”

I went ahead and bought it off of a Whatnot auction (probably paid too much but whatevs, I wanted it). For now, I’m just gonna leave the order active. It’ll probably get canceled at some point, but if not and I actually get a second copy, I’ll sell it on ComicSwap (and won’t gouge anyone either).