Residue can interfere with its intended movement or sensing. Cleaning must follow the owner's instructions for both the control and glass surface.
What the observation means
A removable magnetic control is not necessarily waterproof or dishwasher safe. Soaking it can create a separate problem.
A useful next step
Clean only when safe and cool, using the specified method. If movement or response remains unreliable, record the symptom and accessory condition. Do not add lubricant, dismantle the control or press it harder to force recognition while cooking.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.