graph does not show all plotted points
 

I am a fairly advanced excel user & have plotted graphs with 200+ data
points. Suddenly, I am limited to ~ 6 - 10 points. In the source data bar,
the information looks normal - i.e. worksheet reference and cell range.
However the range is truncated, omitting that last cells. If I am on the
graph and I select a set of data, what appears in the tool bar is the
complete reference, including file name, tab name and cell reference. I
suspect this is why it is truncating as the references are long, but I do not
seem to be able to get around this.