Network Mapped Drive Hyperlinks resolve as UNC in Office Products
After a user inserts a hyperlink to a file residing on a network mapped drive within an Office product, the hyperlink's text displays the network mapped drive path, however the link is resolved as the UNC path.
For example, in Excel if you go to Insert, and then click on Hyperlink the user is prompted to select the file. If the user navigates to a file residing on a Network Mapped Drive, and inserts a hyperlink to that file, the hyperlink will be created to the file via its UNC path instead of its network mapped drive path. After the link has been inserted, the user can then hover over the link and see that the full UNC path has been used when creating the link to the file.
The cause is due to the way Office creates hyperlinks to files. Office products will create links to files using the UNC path and will not use the network mapped drive location, even if it displays it in the hyperlink text.
There is no resolution for this. Microsoft recommends that users insert hyperlinks using the UNC path to prevent confusion in cases where opening a file via UNC or network mapped drive might make a difference in the expected behavior in the file.
An example of where how a file is opened is important can be found listed in this KB article under the section "Scenarios that may cause links to not work as expected."
328440 Description of link management and storage in Excel