I did this in a brand new install to confirm this issue:

Created a new forum.
On front end, created a topic in this forum. All is well.
On back end, changed topic parent from above forum to “No Parent”
On front end, forum page still says “This forum contains 1 topic…” and then (correctly) “Oh bother! No topics were found here!”.

So whats up with the first message?

EDIT: Silly! It seems there’s a “Repair Forums” for that very reason.

WP3.5.1, BBP2.2.4

[@netweb Keymaster 11 years, 10 months ago]

Ha 🙂 https://codex.bbpress.org/repair-forums/

[@mendelk Participant 11 years, 10 months ago]

Thanks 🙂

Was thinking I found an undiscovered bug!