Data changing when adding legend

I have been experiencing the exact same issue. 

Here is the measure: 

Number of Issues during the Period = 
VAR EndDatePerVisual = MAX('Date'[Date])
VAR StartDatePerVisual = MIN('Date'[Date])
VAR RESULT = 
    CALCULATE(
        [Number of Issues],
        REMOVEFILTERS('Date'),
        Issues[Start Date] <= EndDatePerVisual,
        Issues[Due Date] > StartDatePerVisual || ISBLANK(Issues[Due Date])
    )
RETURN RESULT

It's really easy to visualize this problem when using a "Line and clustered column chart:

The configuration of this visual is here: 

The measure being stored in "Column y-axis" is the SAME measure in the "Line y-axis." But yet the total value for the line and the columns are different.