bbPress.org

topic_time is meant to be used in topic loop, not a forum loop so it doesn’t know the last topic id.

You could get around this by passing the last topic id in the topic_time however you’d have to do a custom query to determine the last topic in a forum, as it’s not stored/available by default.

I think I’m going to make this into a plugin “forum_last_poster”

update: I seem to have finally made it work!