I have not heard of Love N Logic classes.
Maybe she finds comfort in the one area of her life that she "gets". When she is tired or frustrated, she gets overwhelmed over her loss of control in whatever is going on and this is one area she can control - albeit in not the sociably correct way. You are the one person she can direct her anger at so she shows you that she can do as she wants with this the one thing she can control to get back at you for whatever.
I am sure that once you find the answer to the other issues, this one will settle down. Whatever method you use starting now, remember, that it will most likely get worse before it gets better as she tries to discredit that method. So, choose a method and stay with it for atleast a week regardless of if it stops working. It may start working again the next time or next day or two. She will think, "What just happened? I thought I got around this one already."
So, what steps have you taken to get help for the violent anger outbursts? If you are feeling this is more than a regular temper tantrum, follow that feeling and seek out help. Others on board will be able to direct you if you need suggestions - I know only to ask your daughter's doctor.