In the screenshot attached you’ll see that scores 0/10 1/8 1.5/10 2/10 0/10 3/10 are all being dropped but 0/5 is not.
When using the lowest or highest score rule, Canvas considers how the rule most negatively or positively affects the student's overall score. In some cases, point values may be considered more important than an overall percentage score. For example, an instructor may set a rule to drop the lowest score in the Assignment Group, where a student with a failing grade earns a 100% on a 10-point assignment and 75% on an 100-point assignment. Even though in the first assignment the student earned 100%, the 10-point value is not as significant (as compared to the 100-point assignment) and will be dropped because it has a much lower impact on the student's overall score.
The 0 out of 5 counts -5 against the assignment group, while the 1 out of 10 counts -9 against the group. Hence it get's dropped.
Is this actually the expected behavior?