My prisoners are all gone!

I was wasting a lot of Vaegirs from my base at Slezhk.  Kept capturing them Vaegirs so I kept sending troops to Reyvadin.  Next you know, much later on I find that Diplomacy seems to arrange to lose those prisoners.  Really troublesome.  Has anyone else encountered this?

yep it's a bug

Sad, but I can't complain.  Spending about 10,000 denars on excess soldier salaries as it is...