[@netweb Keymaster 12 years, 11 months ago]

Run each of these repair tools one by one:
https://codex.bbpress.org/repair-forums/

• Recalculate the parent topic for each post
• Recalculate the parent forum for each post
• Recalculate private and hidden forums
• Recalculate last activity in each topic and forum
• Recalculate the sticky relationship of each topic

If this still does not fix the issue please cteate a ticket on Trac so we can look further into this.

https://bbpress.trac.wordpress.org/