Steps to reproduce:

1. Go to your forum preferences and set 'Use experimental nested discussion view' to Yes.
2. View a forum discussion in experimental nested form.
3. Reply to a post and click Advanced.
4. Enter a different subject for the reply and a message then click 'Post to forum'.
5. View your post on the forum discussion page.

Expected result: The changed subject for the reply is displayed.

Actual result: The changed subject for the reply is not displayed.