All answers correct, score still comes at 90%

Hello,

I've been doing a lot of courses in Rise, and in all of them I have made the same type of test: 10 questions, 70% passing score, unlimited tries, with both multiple choice and multiple answer questions.

I haven't had any negative feedback about it, but yesterday a client told me he had all the answers correct, but the score still came at 90% instead of 100%. He had pinpointed the question he thought he wasn't getting right and wanted me to confirm the correct answer, so I did the whole quiz by straight up copying the answers. This should have got me a 100%. Still, I got 90%.

What could be the cause of this? It makes no sense to me, because I'm 100% sure the answers I put when I tested it were the right ones. In this quiz in particular, all the questions were multiple answers, if that is of any help.

Thanks in advance!