At a guess insufficient speed, Initiate geared too highly, or too much potency.
You are sending in a burner team first to soak up isolate aren't you? And you know it's basic attacks only during topple?
If you are lucky, when Traya rises from topple you can get a second topple straight away if Asajj's TM is high enough and she takes out the sabers with her AoE. She resists everything on the second topple, and it's pretty much guaranteed to be a solo from there.
Final question, and I'm only asking as I had this brain fart last week, you have MT not Asajj in the the leader slot don't you?