AI in Might & Magic: Heroes VI

I've played all the games in the series, and I've never encountered such problems with the difficulty level. I chose my favorite map from Heroes 5, "Ascension to Power." I selected the easiest difficulty level and also chose the easy level for each AI opponent. Out of 6 players, I left only 3. I played the first time – I was defeated in the 4th week. I played the second time – I took into account the mistakes from the previous attempt and, by the 4th week, I managed to defeat the guardians to get out of my "sandbox." I ran into an AI player and got beaten again. I looked at the statistics: one AI player managed to conquer half the map, another took 2 out of 6 cities, and I was left as the last one with my city. How is this even possible on the easiest difficulty level??? In Heroes 5, I played on medium difficulty and never experienced such problems.