It only took me a few years to realise the problem, but I've finally identified what was wrong with the Shimmerene Soiree Gown. Most dresses from the Crown Store are rendered under the skirt, so that when our characters run, it looks more natural, because the colours under the skirt match the colour of the skirt itself. However, this popular, gorgeous gown has not been rendered properly under the skirt, so when you run, you see two feet bobbing up and down in a black void! It looks extremely weird. Please fix it, ZOS.

Running animation with Shimmerene Soiree Gown:


Running animation with Crystal Tower Sapiarchs' Gown: