There is (I think not was) one teacher who is atrocious in her approach and expectations from children.
My kid would come up with some excuse to avoid going to school. We could not figure out what was wrong. We even took him to counseling (poor kid in retrospect).
Finally, we figured out it was due to the teachers and their behavior with children. Our feelings/conclusions were corroborated by other parents as well. We put him in Clarence and he is very happy and does not want to miss school even one day.
So....go figure!