How does a fully refunded batch end up back in available batches?

So I took a Petco batch for 1 item, 12 units. After I hit start I get the "you're all done!" popup. I see that the previous shopper let the customer know it was out of stock and if they wanted something else, the customer didn't respond so it looked like the shopper refunded everything.

I still ended up looking cause I won't have a pup going hungry and whaddya know, there were plenty of the kind they wanted just in smaller cans.

Was it a glitch that the batch became available again (about 30 minutes later based on the timestamp in the chat and when I accepted it)? Did the other shopper get any pay out or a ding on their cancellation rate?

I have no idea if the customer even knew about this cause they never looked at the chat or approved my replacement but it was a no tipper anyway so I just hope the dog is happy!