Hi Jonathan,
according to SAP note 1846194 - Lack of permissons when using AFL
You should
- Never grant any kind of access to schema _SYS_AFL to any user.
- Never grant any AFL role to user SYSTEM.
- Never grant execution on a single AFL procedure to any user including
SYSTEM.
If this appears to be necessary to your system then your user setup is
faulty and needs to be corrected.