Total grade with multiple slots

Given the one student having mutiple slots within one Scheduler activity we have experienced bugs with total grade (Grading strategy: Take the highest grade), two scenarios:

Scenario 1:

-First slot ungraded, second slot grade 2.0, total grade 2.0 (so far so good)

-Someone sets the first slot grade from ungraded to 1.0, total grade went to 1.0 (should not)

Scenario 2:

-Both slots graded, total grade correct

-Someone afterwards changes the grade of first slot --> nothing happens with total grade even when it should

-Someone afterwards changes the grade of second slot --> total grade changes as it should