Greetings from Bug Central!
The bug-of-the-month appears to center around John's Hello card. On it, the next and previous member icons do not appear - and you can't go to either of these from his Hello card.
I also managed once to get an empty Hello card - at least I think it was a Hello card - with Unknown for an icon. More on this subsequently if it reappears.
There IS an "unknown" trying to say Hello. From Suzanne's Hello Card, click on John's Icon. There (s)he is: Unknown. Next time, don't be so bashful: We're all friends here.
[Editor's note: Well I'll be damned! There WAS a bug! And it's been there since volume 5! But it's not there now. Thanks for smoking it out!]