Here's the example, https://github.com/Kasheftin/nuxt-bug6.
I just took the example code from https://nuxtjs.org/examples/routes-transitions and placed the pages into the /pages/a folder. Then changed links. Then created /pages/a.vue file with the following content:
<template>
<nuxt-child/>
</template>After that page transitions stopped working completely.
<!--cmty--><!--cmty_prevent_hook--><div align="right"><sub><em>This bug report is available on <a href="https://nuxtjs.cmty.io">Nuxt.js</a> community (<a href="https://nuxtjs.cmty.io/nuxt/nuxt.js/issues/c1559">#c1559</a>)</em></sub></div>