So I ordered one.  It was the only copy in the system, and so I know I ordered "that" one, the one that showed up at 4:00am in the morning.

A day  went by and no acceptance.

Then, order cancelled "I can't find the book"

Curious, we ended up chatting, I was just wondering how a book can go lost in a day after you post it.  As it turns out, the book was posted a long time ago.  So we are both scratching our heads now.

I have it on my WL and that was the only copy in the system when it got posted.  I know it wasn't WLed by anyone else, because it was "available" when I clicked on it to order it.

So how would a book that was posted a while ago end up in books posted today?  :)

Perhaps someone posted it, then quickly deleted it from their bookshelf.  Or posted it and someone else ordered it.  So by the time you looked, there was only one copy posted.

The account may have been on hold, withdrawing the book from the system for a time. Then, when the hold was lifted, the book re-entered the system and was offered to you. System activity takes place around that time in the morning, if the member had a vacation hold set to automatically expire at the end of the day yesterday, the rest would make sense.