Had a teacher in high school tell me my answers were wrong in a specific section of our workbook. He refused to help me figure out what I was doing wrong. Just kept saying “it’s wrong, do it over”. He marked all of my answers wrong in that section of the workbook.
The following year I was reviewing for the certification exam and revisited those problems in the old workbook after having a better understanding of the problems. I got the same answers I had gotten before that were marked wrong. The guy just didn’t like me and decided that I wasn’t allowed a decent grade. .