The Overview tab within Pull Requests is updated by every comment made on the diff, i.e. the comment shows up at the top of the list in the Overview tab. However replies to comments do not go to the top, in a way the user must scroll to find it.
That being said, the feature is not useful for replies, as they may get lost for not showing up in the top of the Overview.
Steps to check this
- Create a Pull Request.
- Add a comment to the PR. Check it shows up at the top of the Overview tab.
- Add another comment to the PR. Check it shows up at the top of the Overview tab, and the previous comment goes down.
- Add a reply to the first comment made. Notice in the Overview tab that the previous comment with its reply doesn't go to the top.