I just created a quiz with two of the questions set up as groups, each set to choose one question out of two, with one point per question. The quiz had 7 total questions, so should have been worth 7 points. Before publishing the quiz, I noticed that Canvas said that the quiz was worth 5 points, and that the two question groups were set to choose more questions than were available (presumably that's why the points added up wrong).
Now that I've published the quiz, the total score says 7, which is right.
I'm not super concerned about the ultimate scoring of the quiz for students: it looks like the quiz gets scored correctly for my test student. I'm mostly curious whether anyone else has seen this bug before?