You skipped the Boris trigger. I just had that same thing.
If you get that trigger then both Ifan and Sabille talk to him.
As for Sabille, when i play with Lohse as main she doesnt kill Zeleskar or get any persuasion checks.
They just talk. Maybe it has something to do with my choices in dialogue with Sabille. And i have an option to let her talk first or not.
