those are ZERO stock from my perspective

Reserved means they are being held for orders which are pending and haven’t shipped yet.

I have two books that were in my pending orders for a few days (one @ $125 and one @ $80). They disappeared from my pending more than a week ago but were never shipped. They now show as Inactive/Out of Stock. I assume the orders were canceled but not returned to stock. They are both textbooks and the season is coming to an end! Any ideas of what might be going on?

Out of stock and not available are two different things.