It loads a channel, however it fails to display left-hand channel list and private conversation lists. After some time I see a box stating "Connection trouble" with following advise "Apologies, we’re having some trouble with your WebSocket connection. We’ve seen this problem clear up with a restart of your browser, a solution which we suggest to you now only with great regret and self-loathing."

Needless to say I tried the advise, without any luck...