For Leah's slave route, I don't know the exact parameters, but when referencing my save, all of my traits were 7,
View attachment 2871611
I had 7 Bondage Affinity with 0 Condemnation,
View attachment 2871612
it was Day 27, and I had completed all of her trainings several times to reach that point. If it still doesn't work for you under those conditions, I have no idea. You should receive a prompt like this when you go to her 'Act' and then 'Bondage' menu, called "Change of Tides". Make sure you leave a save before clicking it, since it will start a long chain of scenes with Leah.
View attachment 2871613
It'll put you in a cell in Luscious Falls, just keep grinding tasks and make sure your Bondage affinity is high and your Condemnation low or zero at all times (I think she tells you, it's either a week or two, or 30 days, something like that), you'll eventually move on from the cell to her apartment. Once you are in her apartment, there will be some looping tasks and you will have reached the end of her current content. The sc*t scene occurs when you purposely raise her Condemnation while in her apartment.