How do I catch the IT issue that's quietly affecting everyone?

You can prioritize now. What still slips past is the issue that is not loud, the one quietly degrading things for everyone at once, precisely because no single person is shouting about it. A problem spread thin across many people can hide better than a sharp one hitting a few. Missing it is not carelessness, it is a genuinely hard thing to see. Widespread issues often show up as a pattern rather than a single alarm, several people mentioning something a bit slow, a scatter of small complaints that seem unrelated until you notice they rhyme. Train yourself to ask, when a few similar tickets trickle in, whether they are really one thing underneath. The quiet system-wide problem is usually assembled from pieces that each looked minor on their own. Once a day, look across the recent tickets for a theme rather than at each one alone. Ask whether three small, similar complaints are actually one big issue wearing three masks. That habit of stepping back to see the pattern is how you catch the thing that is hurting everyone a little while shouting to no one.