[Vuejs]-Vue-router transition suddenly stopped working

There is a <!-- --> comment between

<div class="ulbricht-slice__top ulbricht-slice__hello-world"></div>

and

<div class="ulbricht-app ulbricht-app__hello">

on the copy of your site that is not working. Something is being rendered/removed there.

It may be causing a CSS selector to be applied incorrectly.