Blood Money is broken. It does not turn prisoners to gold, just moves them out of prison.
Game Version:
      
          Steam Public
      
    Platform:
      
          Windows
      
     
Thanks for the report ! 
I had a look into it and I just found the culprit. 
Expect a hotfix very soon : )
 
 
Same. Today (patch 1.6.2 public release, 6/14/17) seems to have broken Blood Money for me-- It moves the units out of the prison and renders them inactive, though occasionally my own minions will be able to attack them and put them back into the prison. Verified integrity, restarted computer, etc, same problem in all modes.