I have an explicit but vague memory from childhood about doing exactly this, not on an essay question, but on a silly questionnaire like “What are you thankful for this Thanksgiving?”
All the other kids wrote things like “I’m thankful for the food and my family” and I had a very difficult time with it because I felt like it was not at all allowed for me to be thankful for food or for family (or a couple other things that had already been said aloud) and I had trouble thinking of other things to be thankful for.
I remember someone eventually understanding why I was having trouble but I don’t remember how they reacted or what ended up happening though.
I had a similar issue in childhood. (I also had what seems to be a related issue that gave me a lot more trouble, which was that I didn’t like writing things that weren’t strictly true, and this made giving example sentences for a dozen vocabulary words a week REALLY painful.)