Hi @Pturnbull ,
Great question! It sounds like the discussions redesign was turned on for your Canvas instance or course. This is an improved UI experience for discussions. Here is guide that does a high level overview. The functionality to mark posts as read/unread has not gone away, it is just in a new place! Here you can find a guide that shows you how to do so.
Be sure to also check out some of the cool new functionality as well, like tagging users so they get a notification and anonymous discussions.
