Overview:
A user created all the annotations in a previous document version. Once a new version is uploaded (the text where annotations were made did not change) and the user brought all the annotations from the previous version, the annotations are not linked to the content.
Root Cause:
The option Restore placemarks on brought forward annotations is not enabled (checked) in the Vault.
Solution:
An Admin user can enable this feature from the General Settings section.
Related Documentation:
Vault Help Documentation: Bringing Forward Annotations