Playing as Mastermind, I converted a Sheriff. That player was still displaying a Sheriff portrait (even though he was “Marshal” in the list) and could still use Sheriff abilities for a day. Then I got exed (:() and he became an Assassin normally.
At the end of that game, the table displaying player names was also completely bugged (it was just a list of “Player name, Start Class, Final Cass, User name” repeated 16 times). Gold was displayed as “you earned %GP% gp” instead of the amount I won.
Screenshot courtesy of that player: https://steamuserimages-a.akamaihd.net/ugc/924801404259672731/FED096F0628600617B67F73E07B1FE232E536927/