Tooltips don't filter data properly

I'm currently using a line chart for which by default tooltip visual is correct and displays as intended.  I would like to add a data field into Tooltips, but when I do the Alpha Numeric Result displays the same result for every instance of hovering each independent site.  For instance...  I would expect to see A3, A2, A3, B, C, A2 dependent on what I hovered over in the line chart.  It seems to just capture "A3" or "C" dependent on choosing first or last regardless and ignores any filtering.  So basically just taking result of one Site rather than deciphering the independent site being hovered over...   Currently I'm bringing data from a separate table for the tootip add.  Is this is known issue with Tooltip function?  I've still struggled to make it work within the same data table...