Activating chat panel
If you click on the down arrow on a select tab there are a bunch of checkboxes for what sort of message to show. Make sure you have the relevant boxes checked.
Yes, they are checked, where appropriate. That is what baffles me.
That sounds like a bug. Try checking them all off, then on again. Coordinate with a friend to group up and test if you can see their comments. Check your settings, too, I think there are different font sizes available, maybe yours got borked somehow?