>>>Testing Chatter's forum visibility.
>>>
>>>UPDATE. So, it seems to be only Chatter/Chatter category not visible anymore.
>>
>>I can see it.
>
>I know I had it filtered long time ago. But up to yesterday I was seeing everything in the Chatter forum. Now it is probably respecting my original filters.

I seriously doubt their originality, though. I've seen such filters elsewhere.