As a general rule, authors only see content in the Admin Dashboard and in the app if the content is in one of the content packages assigned to them. Authors are assigned to content packages either via groups or via the individual allocation of content packages.
Content that is not visible to authors is displayed as locked in the Admin Dashboard. In the Admin Dashboard, they are still visible in the library so that the sorting of the individual elements can remain correct.
This results in the following rules for the visibility and the right to edit content in the Admin Dashboard:
Content that is in a content package that has been assigned to the author's group
Content that is in a content package that has been assigned directly to the author as an individual content package
The following also applies to visibility in the app:
Additionally, content that has been assigned to the "Everyone" content package