Adobe ACROBAT 3D Manual page 561

Commenting on 3D designs
Comments added to a 3D object are associated with a particular view. If the view is changed--for example, if the 3D object is rotated or moved--the
comments are no longer visible. If you don't want a comment to be associated with a 3D view, add the comment outside the 3D object area.
When the view of a 3D object is changed, any comment associated with that object disappears (right).
To add comments to a 3D object:
1. Select a tool from the Commenting or Drawing Markups toolbar. (The Text Edit tools have no effect on 3D objects.)
2. Add a comment to the 3D object area.
When you add a comment, Acrobat 3D automatically creates a new view. If your comment disappears, click this view to see the comment again.
To display comments:
Do any of the following:
Click the view in the Model Tree that contains the comment.
Click the comment in the Comments list. The 3D model returns to the view in which the comment was created.