After several days of not having the very useful TUJ add-on working, I did some digging and found that the interface was still set for 5.0.x when downloading the update. i.e.
I manually edited TheUndermineJournal.toc file to the current 5.1 Mist of Pandaria releaseCode:## Interface: 50001
The add-on appears to work properly. Is this something that needs to be done on all realms, or was I just unlucky with H-Feathermoon (US)?Code:## Interface: 50100