This, I think, is a bug but I'm not sure.
I had a lot of comments to moderate and I clicked on one IP address to only see the comments from that IP. It showed me three. I deleted all three and then showed me no more comments (should have been more than 20 remaining).
Normally there is a link to remove the IP comment filter but it vanished when I deleted ALL the comments from the filtered IP.
I tried logging out and back in but still nothing. I know I have many pending comments but I cannot see any in the list. I also cannot see any of the comments I've approved over the recent weeks. Again, I think it has applied a filter but I don't see how
to remove that filter now.