Just figured out the problem. I was mainly encountering problems when using report variables to control determine when group headers and footers were being printed (since I was outputting the "summary" info as part of the report cursor -- mainly because I needed totals in each group by category). As it turned out I just needed an extra field in the cursor that indicates if the record was a summary item or not (in which case I don't emit a header nor footer).
Isn't it funny how the solution to a problem is easy once you know the answer?