Creating Dax code to dynamically calculate a "Not Group" value based on multiple slicers

Thanks for the shoutout, JoRo50!  I loaded your sample data and was able to get the results you specified in your examples with these measures:

% Completion = 
VAR SumEnrolled = SUM('SampleData'[Enrolled])
VAR SumTaskComplete = SUM('SampleData'[TaskComplete])

RETURN
DIVIDE(SumTaskComplete, SumEnrolled)

% Complete - Non-Group Rate = 
VAR ThisInstructorStatus = MAX(SampleData[InstructorStatus])

RETURN 
CALCULATE(
    [% Completion],
    FILTER(
        ALLEXCEPT(SampleData, SampleData[Division], SampleData[StudentGender]),
        NOT(SampleData[InstructorStatus] = ThisInstructorStatus)
    )
)

Does this get you what you are looking for?