Unfortunately, I can't post the spreadsheet due to proprietary data and I can't figure out how to duplicate the issue.

I have seen this situation in maybe one out of every several hundred or so spreadsheets I've developed. Unfortunately, I've developed more than several hundreds of spreadsheets, so this happens once or twice a year for me.

I have a spreadsheet that works exactly as it should. I refresh the source data periodically, refresh the pivot cache and the pivot table responds as it should. Then after a dozen refreshes or maybe 100 or 1,000, the pivot table starts yielding bad results. There does not seem to be anything I can do to jar it into producing the correct results. So I build a new pivot table with the exact same definition as the malfunctioning pivot table using the same data source as the original. The new table works. The old one still malfunctions.

There is an expression that insanity is doing the same thing the same way and expecting different results - has Excel gone insane?

So my question is, has anyone else seen this kind of thing, and is there a cure other than creating a new pivot table? In the past, I have sometimes managed to fix the situation by changing the source on the bad pivot table to a new data source with the same format as the original and then switching it back.This doesn't always work.