Round table

What exactly is the problem? Diplomacy, even considering the modifiers, doesn't guarantee 100% success in annexing. The army has been changed. The hero's parameters have been changed. There has been a change in the formula for calculating the probability of annexation. The probability has slightly increased. But now, the probability of non-annexation has played a role. In short, if you have nothing else to do, take a save file and run some experiments. I remember many similar cases from the classic Heroes of Might and Magic, where neutrals, despite an increased army, would flee.