Vingalmo's quest + custom follower spouse = bug? [Dawnguard DLC]

[Soulkey]

Vingalmo gave a quest to turn the wifey into a vampire, just like Cairine before.
I use Vampire's Seduction and the game functions normally up to this point, after my char bites her though, nothing happens. She just keeps walking in the same place, and the quest wouldn't update.

Using this follower mod btw. She has the vanilla dialogue set:
http://steamcommunity.com/sharedfiles/filedetails/?id=258840323

I'm asking this because this mod seems to be pretty popular so maybe someone can give me a clue what is wrong.

PS: All unofficial patches from Arthmoor are installed and set with LOOT into correct loading order.