<Playground> is not rendering anything inside

[alinazamorskaya]

For some reason the <Playground> component is not rendering anything inside it. Would you have any idea why?

This is my Alert.mdx file:

---
name: Alert
menu: Components
---

import { Playground, Props } from 'docz'
import { Alert } from './Alert'

# Alert

## Properties

<Props of={Alert} />

<Playground>
    Test
</Playground>

It is rendering the playground box but there are nothing inside it. In this case I would expect to see the word Test at least. But, if I take Test out of the <Playground> component then it renders.

[adamkudrna]

Duplicates #1552.