In Vault Workgroup, Collaboration or Manufacturing you created a new user property called, for example, "My description" and you mapped it to the "Description" Inventor iProperty (or any other property).
You added the user property "My description" column in your Vault interface but values are empty.
First of all you have to be sure you associated your new property to the right Category (<Base> Category for non controlled files).
You assigned your Category correctly, but you still notice that no value will be displayed for previously vaulted files, meanwhile the value is correctly filled for new vaulted files.
You also notice that previously vaulted files don't have the new user property "My description" in the Properties tab.
This is because the already vaulted files don't know about the new user property "My description".
Already vaulted files need to be checked out and checked in in order to obtain the new user property definition and value.