You can restore the vast amount of your SharePoint data including metadata and configuration settings. However, certain data cannot be restored if parent content or configurations (such as views, permissions, etc.) are missing from SharePoint. Without this, there will no be a place to restore it to or SharePoint will not know how to display the data.
Due to this, we always recommend you restore data at a the highest appropriate level so that data is restored in tact, together with data that defines how the data is shown and who has access to it. For best practices in restoring your SharePoint data, refer to: How do I restore my SharePoint data?
Please also note that you cannot restore user-related data, metadata, permissions, and assignments if the user has been deleted from Microsoft's Active Directory.
Also note that you cannot restore a Subsite or data from a Subsite if the Subsite in SharePoint has a different ID. For example, in the case that a Subsite was previously lost and created. The Subsite and items will be skipped. See also: What happens to my SharePoint data when I restore?
Listed below are specific cases when objects will not be restored or will be restored with missing elements:
Site Content Type
Site Content Type cannot be restored if the Site Column or parent Content Type is not present in SharePoint.
Group of people
If you restore a Group of people, users that have been deleted from the Office 365 account will not be restored – all others will be restored.
User Assignments cannot be restored if its User Role not present in SharePoint
List Content Type
List Content Type cannot be restored if the parent Content Type is not present in the SharePoint Site and the required List Column is not present in the List.
If the List Content Type of the List Item is not present in SharePoint, then the item is restored with the default content type
If the List Column of the List Item is not present in SharePoint, then the item is restored without the column's properties.
If the List Column of the List View is not present in the List, the View will be restored without the column.
An Item Permission cannot be restored if the Site, Subsite, Permission Level, Group Role, User Role, List/Document Library, or List Item/Document Library file is not present in SharePoint.
A List Permission cannot be restored if the Permission Level, Group Role, or User Role is not present in SharePoint.