The hob detects or heats the area in contact with the cooking zone. A wide upper rim can hide a much smaller base.
What the observation means
Manufacturers specify suitable cookware dimensions for particular zones. A pan can therefore look large enough while presenting an undersized magnetic or contact area.
A useful next step
Measure only when cool and compare with the manual's guidance. Select a suitable zone or compatible pan rather than trying to force detection with maximum power. Do not use an unapproved adapter plate to make an unsuitable base appear larger.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.