For induction cooking to work at all, the cookware needs a magnetic, reasonably flat bottom — a quick way to test that is seeing whether a refrigerator magnet grabs firmly onto the pan’s underside. Warped pans, some stainless-clad cookware without a magnetic layer, and aluminum or copper pans without an induction-compatible base are all common, entirely normal reasons a zone won’t detect a pan.
If a pan that worked reliably before suddenly isn’t detected, or if no cookware at all is detected on a given zone, that’s a different situation — pointing to a coil or sensor problem rather than a cookware mismatch, and worth a diagnostic visit.