[Fern]

It turns out that the line breaks working is entirely determined by whether there's an apostrophe in your intro narration or not, regardless of the method being Enter/Shift+ Enter. If you're using any apostrophes in your test, that's probably why:
 

 

 
It's worth noting the text looks like this after you submit the house intro narrate and open the editor for it again, which doesn't look intentional:
 

 
Additionally and I'm not sure why, but there's a little space at the start of the text when the narrates pop up. Don't know if that's a bug or not but might as well mention it.