After the recent updates of the tagging plugin and Jenkins, the Module URL and Tag URL are unusable (see attachment).
Previously, the screen used to have pre-populated textboxes to allow you to see the revision being tagged and the Tag URL (to which you could change if need-be).
Now, both textboxes are no longer visible.
Steps to get to the page:
Build History -> (completed) Build -> Tag this build
(see attached screenshot)