In some cases, it has been seen that Data reduction using multiple fields often results in inappropriate results.
Normal section access will work with multiple fields but only if each user has only one record in the authorization table.
If a user has several records, we need to implement the concept of "Authorization key".
Environment:
Qlik Sense Enterprise on Windows
QlikView
Authorization table having more than one record for one user.
See Data Reduction Using Multiple Fields on the Qlik Design Blog on the concept of Authorization keys.