I removed the joined data source (just kept my primary table) and it is still doing it. I select a cell with 3 records (Sum(number of records)) in it, and click View Data. And get the correct Summary. Then click Underlying and it still gives me 75,000 results. I can't for the life of me explain this or understand it.
Any immediate help would be appreciated!
Found a clue ("partial answer"), it has a problem with Underlying when there is Blended Data. Here is the support article, which only partially answers the issue.
I tried the workaround stated, and it did nothing for me. However, if I unlink the blended fields, then I click the Underlying data and it's correct (6 rows, 10 rows, etc... not 75,000+)