Word 2007 bookmark disappears on other PC

[happysad]

I have a strange problem with a bookmark that disappears when I move a Word
2007 document/template to another PC.

This is how I do:

Create a new document
Insert->Header (different 1st page).
Double click in the header on the first page, delete its contents.
Developer->Insert Content Control (Text)
Select the content control by clicking the little blue "flag" on its border
Insert->Bookmark - enter a title and dismiss the dialog - verify that there
is a bookmark by clicking Options->Advanced->Show bookmarks
Save as template (dotx) or as document (docx), it doesn't matter.

Now move the doc/template to a different PC, virtual or physical, it doesn't
matter.
Open the document/template by double-clicking its icon. The bookmark around
the content control is gone.

Note that the bookmarks will stay in the document if if they are located in
the main document, or outside a content control. However, it doesn't seem to
matter if the content control is locked or not.

What do you think? Is it a bug, is there a workaround (other than ditching
the content control)?