Also getting the same issue with Monster Hunter spells, at 16 int there is 1/day level IV spell which is Halt Undead (this spell works). Also to note is that other than Halt Undead none of the other spells seem to work, they cast and then have no effect.
Seconding this. I had 14 int and was a level 10 monster hunter, 5 Ranger, 5 Barbrian. I had complete access to my first circle spells but the higher levels were unavailable to be selected. I was able to activate the 4th circle spell, halt undead, but it wouldn't let me select from any of the other spells.