The firewall settings shouldn't allow you to be in a channel with other people while at the same time blocking the channels list. The most likely causes:
1. You're on a defective server that doesn't send the list, or one that doesn't actually have any channels. Make sure you're actually on the network with: //echo -a $network
2. Try disabling your scripts with "/remote off" and see if the problem still exists when you do /list *again*. Then turn back on with: /remote on
3. Maybe you have something in the list icon, 4th icon fom the left in the icon bar. Is there something where you're supposed to match a text in the topic? Or you have * in the "hide channels" box? Or have minimum users set to 9999?
If #2 solves the problem, you've got a script interfering with the 'raw' event, 322 and 323.
If you type "/debug @debug" in that server's status window, when you do the /list command again, do you see the incoming messages flooding the @debug window?