It's showing up fine for me. Do you have a screenshot of what you see in the forum listing page? I checked your profile to see if you have disabled certain forums/categories to be hidden from view, but you haven't, so that doesn't seem to be playing a role.
I don't know if OP and I are talking about the same problem, but sometimes the page where it lists all the forums does not render completely and as a result you see few forums missing on the lower end of the page.
Is this a recent thing or has this been going on for a while? When this happens again could one of you try and reproduce this with firebug (or some such tool) and post some details like the response status code and related details like bytes sent (I think some screenshots of those details would help too).