When it comes to closed-source software developed opaquely by for-profit corporations, particularly the huge, monolithic ones like Microsoft, I generally have the attitude that, if I do discover a problem:

1. They won't take my detailed report
2. If they do take my report, it goes straight into a shredder bin (or a massive queue where low priority problems go to die, which may as well be the same thing)
3. If they do read my report, then it's likely something they already are aware of
4. If they don't know about it somehow, the issue is probably so low-priority and niche that it wouldn't escape the backlog anyway

Probably not nearly as bleak as I make it out. But when you can't see the process, how can you tell?

With open source projects, these things can all still happen, but at least the process is more transparent. You can see exactly where your issue is, and what's been done to it so far, if anything. Other users can discover and vouch for your problem. And if the dev team takes pull requests, and you are willing, able, and permitted to contribute, you can make the fix yourself.