Tableau's first release for nested project is 10.5. In 10.5 release, only top parent project can be locked. When parent project is locked, all its child project permission is also locked. If parent project is unlocked, you can't lock any of its child projects. This idea is to allow child project permission locked while parent project is unlocked.
Some more details:
- When a child project is locked, all its sub project should be locked automatically, and all workbooks & data source permissions will default from locked child project
- When a child project permission is changed from locked to unlocked, all its sub project should be changed to unlocked automatically. All workbooks & data source permissions remain the same and are ready to be changed by owner/project leader/admin
- When a paren project is locked, all its sub project should be locked automatically (current feature, no need to change)