I think I found the bug preventing the strip club storyline from triggering: in the attached screenshot you can read that I can not blackmail Gabrielle and I have to find out what she does at night, but instead I can blackmail her and I already know about her job at the strip club.
I raised her obedience and went --> blackmail --> demand etc. I know there are other ways to find out (searching her room and/or wandering the streets to find the strip club and then confront her about her being a stripper...) so maybe the path I used blocks the strip club storyline? Is there a way to check if Gabrielle's conditions are met and change them?