Roundcube webmail not showing all messages?

[#1]

When I use webmail log into my catchall mailbox to check the spam for false positives, only a handfull get displayed (about 20).
There is no mention of there being any more messages.  However, if I view one of the messages, then go back to mailbox, a load more emails have been 'discovered'.  Is this normal?

[#2]

http://community.plus.net/forum/index.php/topic,101929.0.html may be relevant

[#3]

That is exactly what I get.
Will post on that thread.