This is deliberate and allows you to hide or display data
using either the filter options (Data menu),subtotals or a
macro to toggle the hidden status of the rows containing
the chart data.
You can unselect this option (i.e. diplay hidden data even
if the rows are hidden) by first activating the chart and
then selecting Tools|Options|Chart tab. Then unselect
the "Plot visible cells only" checkbox.
Regards,
Greg