[@robin-w Moderator 6 years, 9 months ago]

you are assuming that because it doesn’t work for you it doesn’t work for anyone 🙂

It works fine on my test site.

so create a new topic and subscribers to the forum get an email when a new topic is created.

If this is not happening for you, then it could be a theme or plugin issue

Themes

As a test switch to a default theme such as twentyfifteen, and see if this fixes.

Plugins

If that doesn’t work, also deactivate all plugins apart from bbpress and see if this fixes. if it does, re-enable one at a time to see which is causing the error.

Then come back