This is a bug. So, when you hover over a pie slice in the popup, you'll see the raw data value, not the normalized value. However, the pie itself should look correct. Normalizing the data does impact the actual numeric value being charted, but the ratios shown by the pie slices don't change, because they are a percentage of the whole.
As a workaround, you could add a field that represents the normalized value.
Thanks,
Mike