Created an account just to take part in this thread. Have the exact same problem, can't make Malady use her flood on the candles.
This makes me really sad. While all the character quests seem interesting, Lohse's seems the best one to me. Having an archdemon residing inside you like a parasite, and having to snuff out millions of souls to cleanse yourself is just epic. And sad, as Lohse otherwise is so easy-going with her jester-puns and bard background.
Adrammilik is also a really cool villain. The dwarves ominous saying "The Doctor is in" is really chilling.
Game-info: Playing co-op with my friend. Lohse is my main. Sebille is my companion. My friend has Red Prince as main, and Beast as companion.