Why does a forum topic show more comments than I am able to view?

There are a couple of reasons why the number of comments listed next to a forum topic in the index will show more comments than you are able to view.

If the member who posted the orignal thread posted to multiple groups and you do not share the same group(s), you will not be able to see the comments posted by members of the other group(s).

Also, the comment counter keeps track of private comments posted only to the original forum poster. Group members won't be able to view these comments.