Setting up a piechart with a cell range from which to take the colours for the pie slices, does not use the same colours for displaying the piechart legend.
I have a printscreen but apparently I can’t upload it here.
Hello,
this is bug #tdf96332. You may want to leave a comment in the report (incl. your system information from Help -> About LibreOffice), that the bug still exists.
Hope that helps.