I have a report that has several sub reports for presenting related attribute information on a variety of subjects. My experience is that report pagination seems to cause the handling of sub reports to occur out of sequence. From my perspective, it is as though the report engine looks ahead to any component that can fit in the remaining space before generating the next page. The result is that a sub report may not complete its processing before the next sub report begins presenting data.
I think it is a good assumption that a sub report should complete processing all of its data before moving on to any other report element. But this is not so.
If you like, I will produce a screen cam movie to demonstrate this problem.