Datasets list next to plotter show too many data sets

[Acefall]

After changing plot types form map to bar char there appears an additional data set in the list next to the plot. This can be repeated multiple times. Then when I press "x" on one of the data sets, all are closed.

[mmaelicke]

Thanks for reporting.
Each time you click on Add, a new dataset is added to the legend. This is actually intended behavior. But one click on x should not remove all, that's a bug.
I will look into this and maybe rethink the adding behavior as this is not super intuitive.