Forum post notification list gone?

Forum post notification list gone?

When I go to create a new forum post in an existing project, I no longer see a list of project users from which I can choose who to include in the notification list for the post (causing an email to be sent to each user).
The notification section is simply missing.
Thinking that the option to choose users to notify would be offered when I clicked "submit", I tried that, and ALL project users received notifications (NOT what I wanted to happen).

Switching my portal to "Old Version" format brings the notification list back to the New Post form.

Why has this functionality disappeared in 4.0? Without the ability to direct forum posts to specific users, this communication tool is not very effective.