okay, for Melee! The workaround I have used is click the "Use Melee Settings" box and set the Range to 150,000! My bot has only missed 1 mob in about 30 minutes! :) Hope this works for you as well as it did for me!
Don't forget to click the *Thanks under my post! Thank you and happy botting! :)
[EDIT]
Okay I was messing with is some more and when you set and range box to bot in it stops working again.. It will randomly change targets and never attack. I had to set my bot to "Random" before it would attack mobs the right way. On occasion it will still miss some mobs, but this is a workaround till something better comes along. I will keep working at it until I can find a better solution for you guys.