掲示板 Forums - Redoing terms after mistakes state mastery level is 9

When I had some questions wrong in a vocabulary quiz, and they came for redo, and I did have them correct, it says that the "mastery level stayed at 9" (see screenshot below), even though the mastery of those terms shouldn't be 9, especially after getting them wrong. The masterly level doesn't really get to 9, I believe, but it does restrict me from seeing the correct mastery.

This screenshot was with 窓, although it happens with every word as far as I know. I've got some more screenshots, but it looks the exact same so I don't feel like digging in my phone gallery and posting them:)

When redoing terms and I got them wrong, it does display the correct mastery, although when I have them correct after that, it's 'at 9 again', same with normal terms. It's really only with redoing terms.

Am I the only one having this bug? It has been around for a while (at least for me), but I forgot posting it, and I haven't seen anyone else with the issue.