Sometimes students type an answer to an essay question (classic quiz) but only some of the words are visible. If I select or highlight the entire area, I can see their answer. One student said that some of the words turned red as she was typing - those were the words I couldn't see without highlighting the area.

Any idea why this happens and what students can do to prevent this? This has happened only a few times, but I'm afraid I might not notice that part of the answer is missing and give a student a much lower grade than they deserve.

Answer I can see:

Answer I can see if I select this area: