I got a question on a vocabulary quiz where it asked to pick the kanji for こじん where both 個人 and 故人 could be possible answers. It marked it wrong because I picked 個人 (see screenshot). It usually seems like it avoids multiple choice questions with ambiguous answers so this might be a bug?
When things like this happen, the best thing to do is tap the ? button at the top of the app, then the "report quiz issue" button. That sends me a full copy of your quizzing data (including all the stuff "hiding" behind the scenes), making it *much much* easier to isolate and fix the issue.