Thanks, J.B. I don't think that's it, as I had Order 1, Distortion 1 and Chaos 3 when I got the Archmage skill and I only got 1 intellect and 1 mana. Hasn't increased at all, after subsequent skill picks.
I only found one other topic about this but which doesn't answer my problem:
http://steamcommunity.com/app/289520...2768628398306/