Only use arrangements the hob and cookware instructions permit. Two independent zones are not automatically a combined cooking area.
What the observation means
An unevenly heated or poorly supported base can behave unpredictably. Some models offer a specific bridge or flexible function, but that has its own compatible cookware requirements.
A useful next step
Use the approved combined mode where available and follow its placement diagram. Otherwise choose a suitable single zone and pan. Do not improvise with a griddle or adapter that covers controls or vents merely because it spans both circles.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.