If you haven't downloaded the Mixbus 3 manual or you did a while ago, it is worth downloading it again as they have updated it. The latest one is dated more recently than the previous V3 manual. (check: the date is on the first page)
I am not sure just installing the latest version gets you the latest download manual. It may want to go to the online manual when you ask for it. Which is the latest version of course.
So far this latest release looks very good and is very stable for me.