Persons registered with UWV Cadans with no Professional Grp Code

What causes this issue?

These persons are registered with the Body Implementing Employee
Insurance Schemes [UWV] Cadans.
The Professional Group Code field
for infotype <ZK>Body Implementing Employee
Insurance Schemes</> (<ZH>0409</>) is not filled for these persons.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Error message extract from SAP system. Copyright SAP SE.