Activated the tweak to allow non-human chars to dual-class.
Have a (dwarf) Dwarven Defender that can't multi-class. They have 18 wis, 16 dex, but can't dual-class to either thief or cleric. Not sure if this is because they're a dwarf-only class and so all dual-classing should be disabled?
The mod is definitely active as I dual-classed a half-orc berserker to a thief.
Ended up EEKeeping it, seems to work now.
Cheers.
Sphyxx