Here is something strange that happened.  I have ALL of the books on my wish list set to auto-request.  One of my books was posted into the system, and so I got an email saying that I had requested the book.  Then, later, I got another email saying that the book couldn't be mailed.  (This happens from time to time.)  The PBS email that told me the book couldn't be mailed also said that the book had been added to my wish list.  It appears , though, that my "automatic request" setting was NOT placed on the book when it was re-added to my wish list.  So, when the book was posted into the system the next time, I had to log in to request it.

I guess it would be nice if the autorequest could be placed on my book again, but maybe that is too complicated.  At least now I know that I'll need to check back in and manually re-set the autorequest the next time this happens.

Yes, you have to put the AR back on the book yourself.

As soon as I get a message that a WL book was canceled or lost and is back on my WL, I immediately go to my WL and set it to AR. It's not a problem for me.