An aluminium body may contain a compatible magnetic base, while another pan may not. The body material alone does not establish induction suitability.
What the observation means
The size and construction of that base also affect how the hob recognises it. Advertising such as 'all hobs' should be checked against the cookware instructions and actual condition.
A useful next step
Use manufacturer-approved cookware guidance and avoid empty-pan testing. Do not add loose metal beneath the pan or modify its base. Record the pan reference if detection changed after introducing a new set.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.