Return of Reckoning

I received the in-game mail to start the dwarf shield heraldry quest. I took the attached rune-sealed letter, which is now in my quest inventory. Unfortunately, nothing happens when I right-click the letter to begin the quest. It is just sitting in my quest inventory at this point.

Reloading, relogging, quitting and restarting the game has had no effect.

Anything I can do?

Did you ever find a solution to this? The same thing is happening to me.