When content that inherits access via Sharing from a Notebook is moved to root (i.e. without a Notebook) it is possible that the content is orphaned and no-one has access. Access can be re-established by an administrator via Security Policy. Additionally, a policy that grants individuals Full Control will allow them to grant further access via Sharing.
Workaround: Admin to grant themselves Full Control via security policy, then grant Full Control or another access to whoever needs it via Sharing.