wrong slice in plotting simultaneous pdf built with RooSimWSTool

Similar problem as reported in https://root-forum.cern.ch/t/wrong-pdf-projection-when-using-ploton-with-roosimultaneous/11670 , but with RooSimWSTool in place of RooSimPdfBuilder, which is superseded.

Basically the simultaneous PDF generated with RooSimWSTool works well during the fit, but when plotted in the two different slices, it does not change, i. e. the slice category "peaches" is plotted even if

Slice(sample,"apples")

is requested.

Attached a minimal example where a simple gaussian is used as a prototype and the mean is different for each category. The fit on the generated pseudodata works well, so the problem seems only during the plot.