Maybe you have this already - I'm playing on easy getting a feel for the game - my character has the trait that gives champions / heroes for free...

This was doing very well and saving me some money - but when i got to the point I had researched magic to the level I could hire level 9 heroes I went running over to the two heroes I had seen and I can't hire either as they require -256 gold.  I have 8000+ gold...

I assume this is a bug.  I couldn't find a list of known bugs so I thought I'd mention it...

Great fun so far by the way...