I think a big part of Sabine and Kanan’s conflict in TOTD was that they really didn’t know how to deal with each other; Sabine can’t bear the thought of returning to her biological family after what they did to her so she’s acting out and being much nastier than usual due to stress, and Kanan’s only experience with being a teacher is with Ezra, and Ezra and Sabine are so different that training her is a completely new challenge.