Inconsistency: Group-to-group transfer is only for in-stock quantity

What causes this issue?

A planned replenishment object has been transferred between groups,
however the affected object was not in stock. Group-to-group transfers
can only be performed for replenishment objects that are in stock.

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?

Contact your system administrator to find out why such a transfer has
occurred.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.