I attacked the worm whilst playing as a kingdom sovereign. The tactical battle screen opened and the units stood around. Animations were correct.
However, it seems that the initiative roll did not begin: I was unable to select any units (my own or the enemy worm), no popups appeared when I moused over a unit, and no key-presses did anything.
I was able to skip the battle by clicking the 'skip to battle resolution' button.
