SAP Readiness Check - "No customer found"

Dear All,

I have an s-user linked to the a customer number on sap portal:

When I try to create an analysis on the readiness check, I get an error message saying “No customer found” when inserting the customer number.

Furthermore, I don’t see any customer available in the drop list nor I have a default customer assigned in the readiness check:

Could you please help me understand why even though the customer is assigned to the s-user, I am not able to select it in the readiness check application?

Thank you,

Best regards,
Ayman