Thanks for thinking about my question in advance.
I created a pie chart based on a dimension which is a value list. As a measure, I assigned a value to each value in the value list. The result is a pie chart. The pie chart responds to my selections just as it should.
If I click on a piece of the pie (for getting more infos) and, after that, return to the unselected pie, it stops responding.
If I make a change of the pie chart properties (e.g. allow null values), it starts responding again.
It seems like clicking in the pie chart creates some kind of invisible selection?
Is there any way to resolve this issue?