Do you have the views ordered correctly? The report writer does not sort the data for you based on your data groups. It's up to you to make sure the data is in the right order with indexes or SQL ORDER BY.

To test what you have at the time the report is running, add a dummy field to the detail band with an expression of ALIAS() to make sure the right cursor is selected. If you use indexes, go ahead and add another dummy field to see the order.

One more thing to check .. if the form has a grid on it, programmatically take focus off the grid before you run the report. There are issues where VFP changes the current alias to the one of the grid so it can refresh the grid and that can mess up your report.