Thanks @FreedTerror @gamingislove for the response, for my first problem I found it. it's because I have set the move range or hunting range too short. I didn't expect that was the problem, because I thought after getting out the range, the AI will go back to their position regardless of the detection range. It seems the combatant position is outside the move range or hunting range, yet the detection range is still in range this cause confusion on the move AI decision (idle/hunting/waypoint) I believe this will be an odd settings for the real time battle or open world battle scene.
For second problem, I managed to make it the right composition between the length of animation and the wait node. Seems these two things has to be done right to play good animation.
I have new problem, my AI animation run smoothly it's like, running / chasing player, then when in ability range the AI hit me and does the damage ok. Yet I apply the same animation and it's settings on unity and ork on the player, I run to enemy then I press attack WHILE running, the animation is like perform in half (not finish and also not smooth) but if I attack while no action (is idle) the attack animation run smoothly. I tried to configure the transition here and there, I still can't find the solution, and I think it's not the problem, or is it? Can someone help please?
P.S sorry for my bad english. I hope you guys understand what I am saying.