Oh, for sure I have a growing list of QBO's half-arsednesses :-), but so far I haven't bumped into that particular problem of lack of aging info.
What is it about the Accounts receivable aging summary and Accounts payable aging summary reports that don't provide what you're looking for? Is it that they're not "in detail"? I rarely use the "...detail" version of those reports but now you raise the matter, yeah I see that those group by aging period, but not then further by Supplier or Customer. Bummer.
You're probably already doing it, but my only suggestion would be -- and this I do turn to a lot -- to spit the report out into Excel and then you can do whatever you like with it. Shouldn't be too hard to get that further by-Supplier grouping if that's the issue.