What is a possible reason for the grayed out Restore Version button in the screenshot of the
Database Revision Control while trying to restore Old Structure?

A.
Old Structure was not approved in Smart Workflow.

B.
No Smart Workflow session is started.

C.
With Smart Workflow active, only Smart Workflow revisions could be restored.

D.
Self-created versions cannot be restored if there are newer versions created in Smart Workflow.