Necro won't use any other skill than Weaken. At me is the same. Don't worry, let him, it will bot great. It's not a bug or something. Summon Minion must be used first by you. Then you don't need (if you attack monsters, not bosses) Infect or Command Undead.
And the mage thing, just select Options, and change Rest if HP is < than 300. This is what i use. If continues, it's a bug from the program.
~megenhos