Ref: AW 20110727
Last Edited: August 18th, 2011
When a hyperlink is made to a page in the same file through drill-down, Control+K or on an Up to Parent button, Visio is automatically translating the hyperlink into a formula that will not work correctly after save or export to HTML.
This error can be reproduced using standard Visio shapes with hyperlinks pointing to pages in the same file.
A Visio 2010 and Visio 2010 SP1 error.
Triaster have developed a workaround for this that is effective on Activities drilling down but not Up to Parent buttons drilling up. To avoid this issue altogther you should drill down to an external file.