Since the ticket reporting system is down for understandable late-night reasons, I'll just post it here.
The Chat Transcript Viewer isn't updating continuously as before. If you wanted to view any text you entered/received during a session in which you didn't reboot Adium, you would have to reboot Adium in order to see them.
Good thing is that all the chat histories are being saved if you enabled it in preferences, it's just not updating in real-time. I was panicking for a minute thinking that whatever I just typed was lost and I wanted it to be saved.