Can't dual class AT ALL

Hi, I'm hoping someone can help me. I just got done installing a Big World Setup. Not really a huge amount of mods or anything major.

For some reason, I can't dual class AT ALL, however. I've tested many classes, EE Keeper'd character stats to all 20s to make sure requirements were met etc.

The dual class button remains greyed out no matter what. In fact - even if I use EE Keeper to change my characters class du a fighter dual'ed into mage, upon entering the game and booting up the save, the character is suddenly just a full-class mage! What the hell?

Weidu.log : https://bit.ly/2JtX5vp