How do enemies choose a target to attack?
I play on the last difficulty and expect that the enemies will try their best to defeat me.
Instead of that they
1. Ignore more attractive targets (with lower HP, AC, but at the same time causing decent damage such as a mage or a rogue), but for some reason they focus, for example Half-Orc Barbarian, who in my party has maximum HP, AC, resistance due to Rage, and also Relentless Endurance ability.
2. Moreover, they do this even if my mage and barbarian are standing next to the enemy and he can attack anyone without even moving. Also, if the enemy is standing next to the mage (rogue) and the barbarian is further away, then the enemy runs away from the mage to the barbarian, receives a couple of attacks of opportunity and makes the mage (rogue) feel free for long-range combat without disadvatages.
3. If I understand correctly Ruthless AI option should complicate the game. But often enemies is so busy trying to finish off a character with 0 HP that they don't pay attention that a nearby Cleric removes the dying status every turn with the initial infinite cantrip. Not to mention the fact that the rogue and mage who stand nearby continue to slowly beat that enemy who could kill them in a couple of turn.
That would be grate if you could fix that in your wonderful game.