I never cook with coconut oil at temps above the 4 on my stovetop. More than that and it sizzles out of control, which I can only assume is oxidizing it.. But liver, eggs, and most other things cook perfectly at 2 or 3, so I rarely even turn it up that high. I do sear my steak at the 4, and then turn it down.
Maybe that oil is cut with nasties or not filtered properly, etc.