Recently I notice my book requests no longer carry an 'order more books' button  which used to take me to the senders bookshelf in a single click.

A recent change? Or have I just not noticed ths for a while?

It's usually still there when I order, maybe they put the shelf on hold or have no other books listed. Some people only post WL and keep no active shelf. You probably know this, but you can also click the PM button and then on the member's name when the message window comes up. If you order from the same person it will add on to your order.

I don't have it either. I still have it on swapadvd, though.

maybe they put the shelf on hold or have no other books listed

I've been offered a number of WL books lately, but not one came with the 'order more' button. I did get to bookshelves via the round-about PM method so it's not about having books on hold or none listed..