Thanks for bringing the quirk to our attention! Out of curiosity, which forums have been disappearing? I'm wondering if perhaps it has to do with how recently a forum topic was responded to, or if there might be any other tag that might be influencing where the pages go. Let me know, and I can pass this one along to our engineering team!
Shoot! You're absolutely correct. I can even see on the "Most Recent Forum Posts" that most other threads show their larger sub forum heading, but that the Trail Mix Thread doesn't have that. It's not the only thread without a sub forum, so it seems to be a problem on our end. I'll send this along to our engineers, and hopefully it will be fixed soon!