For some reason, break-before: page does not produce the expected output.

I would like to start on a new page for each new chapter, so I wrote:

.print .chapter h1:first-of-type {
  break-before: page;
}

Problem: this CSS rule is not even part of the rewritten CSS rules injected by Paged.js.

If I write it this way…

.print .chapter h1 {
  break-before: page;
}

… this is how it is injected in the CSS styles:

.print .chapter h1 {
}

The CSS declaration is empty.

And the page break does not happen: