Delivery split does not allow additions to delivery

What causes this issue?

The summarized JIT call split criteria are active.

System Response

The components group can not be added to the delivery.

How to fix this error?

Delete the delivery and recreate it with all the component groups, or
change the summarized JIT call.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.