It is not possible to add a new message within the broadcast messages.
SAP Cloud for Customer.
Reproducing the Issue
Go to the Administrator work center.
Go to the Broadcast Messages view.
Search and open broadcast message LMN (where LMN represent the message id).
In the Messages facet, you can see the Add button is not editable.
It is not possible add message, if the broadcast is already with status active or expired.
The new message can not be added in active/expired broadcast is an expected system behavior.
expired , active , add button , KBA , broadcast messages , LOD-CRM-WKF , Workflow , Problem