To start with i would like to say that I like this game. From here we can move on to minuses.
I have finished necro, haven and orc campaign on hard and even though i found myself in the situation where the AI with 1 castle produced the same amount of creatures as I did with 4 I will not consider it a bug but rather the new idea of hard in Heroes.
But when I started the sanctuary campaign things went berserk completely.
1. On third scenario i found the tear of asha as reward from some ruins even though the secondary involved finding the 4 fragments in order to get it. Lucky me I said but as soon as i built the building the numbers of the creatures to recruit were displayed with minus ex. -56000 or -275999 etc. Restarted scenario and it went fine except this time with 3 fully upgraded castles i was recruiting 98 creatures total per week. Also the necro castles were impossible to convert even though the secondary stated you need to convert all 4 towns.
2. Managed to finish and moved to 4th scenario, where, after getting 3 castles and fully upgrading them (adding to this 2 gold mines) my kingdom was producing an unbelievable 5500 gold per turn. Also i saved and quited watching a creature stack that presented a low threat to my troops. When I loaded the same game the creature stack was now a severe threat and all the stacks around have grown too while I was sleeping.
If anyone played sanctuary on hard and got the same please let me know and maybe someone will bother to fix this because heroes is after all a mathematic game and all this chaos makes it unplayable