Problem:

When removing the second group by from a multi measure report with a stacked visualization,
the stacking stays enabled, although reports with a single group by does not support stacking

Steps to reproduce:

Clearly mention the steps one by one to reproduce the bug. Don’t make generic statements, please be specific in the steps to follow.

1. Create a process instance - count report
2. Group the report by start date - month
3. add a second grouping by a variable
4. Change the visualization to Bar chart
5. Open the configuration popover and enable stacked bars
6. Remove the second group by; 

Actual result :

Bar chart stays in stacked mode and cannot be disabled since the configuration popover does not contain the option to disable it

Expected result:

Stacking is disabled since there is only a single group by