I had a student who though that she knew all the content and then when she flunked the tests she blamed it on me. I reflected and then sat down with her to talk to hr. She stated that she knew the content and that my test questions were the reason she failed.
I pointed out nicely to her that she is on the text all the time and also talks in the back of the room.
The second week she perked up and participated ending up passing the class.
It takes a teacher to go above an beyond to meet the challenging student half way.