Hm..no idea. Honestly, it's not something I've ever used before so I'm not sure how it's supposed to work or why it wouldn't show anything any longer. I'll see if I can find anything about it.
edit: Ok, I found this on the official phpBB forum:
Quote:
Re: 3.0.5 to 3.0.6 View Active Topics not working
Postby Kevin Clark ยป Fri Nov 27, 2009 6:42 pm
There was a bug in 3.0.5 that meant all the forums were used for active topics even if the option was on no.
In 3.0.6 this has been fixed so you need to edit each forum (manage forums>green cog icon) and turn it on for the ones you want to use.
I'm not sure I understand what the difference between this feature and simply looking for new posts? I don't mind enabling it but honestly I just don't exactly know what it does. Care to explain how you utilized it for me? Thanks!