Dynamic `timelineContent` which involves updating the state, isn't rendering the content.

[miral-zymr]

Describe the bug
When I define items, which has the property timelineContent getting appended runtime, in a state, the content is not rendering on the content. The content is getting set on the items array.

To Reproduce
I'm adding the link to the sandbox: https://codesandbox.io/s/infallible-microservice-yzfjvz?file=/src/App.js

Expected behavior
Content should render on the screen when the items are getting rendered.

Screenshot