How do you enable item info popup in chat box?

[AstraMercer]

On one of my characters, when I hover over an item that's linked in the chatbox, there's a little popup that shows details about that item.

On my other character, I can't get this popup to show up, and I'm not sure why. I tried setting the chat settings to their defaults but the popup still won't show up.

Does anyone know what might be wrong and how I can fix it?

Here's an example of the popup box working.