I apologize in advance, because i know there are a lot of similar
posts.
None, as far as i can tell , have a definitive answer as to how this
was fixed.

I have written and addin with a number of custom formulas.
A client has a spreadsheet that gets data from these formulas,
performs simple calculations on it (like determines a percentage) and
uses a range of these values to populate a chart.

When i recalculate the spreadsheet, all the formulas are recalculated
(I use xlc SendKeys CNTRL-ALT-F9) to calculate the data.
However the graph/chart is not refreshed.

I believe this is an Excel bug because
(1) If i save the spreadsheet and reopen it, then the chart is
updated !!
(2) If i simply "delete" an empty row in the spreadsheet, the chart is
updated !!! (go figure). I think i remember reading somewhere that
hiding / deleting rows causes Excel to recalculate or something, but i
maybe wrong.

Is there a non-kludgy way to force the chart to update?
OR
Is there a less kludgy way to force the chart to refresh? (than always
deleting an empty row, and undeleting it - I'm assuming there is a way
to do that programmatically)

How has everyone else handled this ?

Thank you for your response and time.