3418519 - Unable to see add button at placeholder in Notification workflow

When create a notification workflow, there is no add button when want to add a placeholder, but there is an add button if the Rule Type is E-mail. 

Cloud for Customer

1. Go to Administrator Work Center.
2. Go to Workflow Rule Work Center View.
3. Create a new Workflow rule.
4. Go to Step3 Define Actions.
5. Select Notification in Rule Type.
6. There is no add button when want to add a placeholder.
   

In Notification based rule type, only four place holders allowed in the subject.

This is a system standard behavior.

ByDesign 1508 Release: How to create Workflow Rule to send email and notifications | SAP Blogs

Workflow, Notification, Placeholder , KBA , LOD-CRM-WKF , Workflow , Problem