Can you put your bookshelf on hold, but not your wish list?  I ask because I posted a WL book that is now in a 48 WL hold.  Yet when I tried to check their shelf to see if they had anything I might want, it said it was on hold.

They must have posted the book and then placed their account on hold. I've done this before myself. You can unhold your account place a book into the system and then rehold the account.

They must have posted the book and then placed their account on hold

No, I posted the book.  It's now waiting for them to accept, but their account is on hold.

They must've had the book you posted on auto-request but did not have a credit available to cover it.  Thus, the 48-hour WL hold.

Some people put their account on hold when their postage money runs out. 

Can you put your bookshelf on hold, but not your wish list?  Yes. If you put your shelf on hold and have your WL books on auto-request. That the book went into a 48-hr hold instead of the 1-hr of auto-request is odd. The only thing I can guess is that they have no credits and it converted. I would have expected the system to treat it as a non-autorequest, but maybe that's too much for the system to think about.

Well, now the book is no longer on WL hold and is not on my bookshelf either.  In the transaction archive it says it was cancelled by the sender (which would be me), but I did not cancel.  I guess I should relist.  This is weird.

That is very weird because if it was in a WL hold you couldn't cancel it even if you wanted to. This might be a good one to use Contact Us and see what happened.

Some people put their account on hold when their postage money runs out.

This is what I had to do recently.  I had been mailing out a book at least every other day and sometimes 2 in one day.  Had to scale back until payday.  HA!

It's still set up to give 48 hrs if the autorequest person is out of credits.  Although I would think it wouldn't do this if their account was on vacation hold.  So this seems odd especially if it says it was cancelled by the sender.  When a WL offer times out from not being accepted by the wisher it shouldn't show up on your Transaction Archive at all.  It should just go to the next wisher or on your shelf.

This keeps getting stranger.  So I emailed TPTB and they cancelled the transaction.  I reposted the book and waited for wisher to accept.  Last nite I checked and it was no long waiting and had been removed from my shelf.  I posted it for the 3rd time and guess where it went - to the 1st wisher whose account is on hold.  Maybe I should give up and offer it in the historical fiction forum.

Maybe you could see if the pattern repeats itself, and if it does, let the PBS team know that you are in some kind of twilight zone here.