Yet another post about items disappearing from the intray

More specifically, if I try to create a new bill from an in tray document, then discover there was a PO raised, I conver the PO to a bill. Unfortunately, when I go back to the in tray, the document is no longer there to attach to the newly created bill. It is also not attached to the bill. 

I also tried refreshing the screen. It's like the software thinks, well, she tried to use this one already so let's get rid of it.

On the other hand, If I start to create a new bill from a document and change my mind and cancel out, then the document is still in the in tray, ready to be processed again later. This is what I think should happen in the first scenario as well.

Yet another thing that used to work but now doesn't. Please fix it.