What causes this issue?

You want to import a substance from the regulatory list; however, either
no listed substances exist for the current regulatory list revision or
all of the listed substances in the current regulatory list revision are
specified as declarable substances for the selected component.

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?

Ensure that the current regulatory list revision contains related listed
substances that are not marked as declarable for the current component.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.