Heat transfer and stable support depend on the cookware meeting the surface appropriately. A rocking or deeply ridged base can perform differently from the recommended design.
What the observation means
A pan that was stable on a gas support is not automatically ideal on a flat glass surface. Its material and size also affect cooking.
A useful next step
Use the hob's cookware guidance and inspect the cool base for damage. Do not press a pan down or drag it to improve contact. If a zone remains ineffective with suitable cookware, describe that observation separately from a pan-fit problem.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.