The segment (side view) always shows the gradient and route profile of the section you are on. The problem is that it changes every time you divert onto a new section. When you are riding a Zwift defined route, the profile should be for the whole route (all segments combined) and only change if you divert.
zwifthacks.com may have some add-in that enables a full route overlay, but i’ve never downloaded it to try.
Shouldn’t this be something Zwift does themselves rather relying on an external to work out a away around doing this?