The pop-up screen will appear for a second and disappears when we click on the pencil icon on a specific transition when the project is in a self-service mode. Please see the below video capture for reference.
Steps to reproduce:
Install the Delegated Project Admin Pro for JIRA app.
Go to a project that uses DADMIN Self-Service Mode.
Go to the workflow section and click on the pencil icon for any transition.
Pop-up screen will appear for a second and disappears.