I am on Unity 2018.2.18 with Vuforia 8.0.10 (tested on Editor and Android) and an Editor key.
I imported the classic VuforiaMars_ModelTarget (or a database that contains only one model I created with the ModelTargetGenerator, only one database at a time).
When I choose "GuideView2D" and the Front image for the Mars Model Target, it appears; but when I choose the Rear GuideView, it doesn't show on screen.
The same thing happen with my ModelTargets. If a ModelTarget has more than 1 GuideView, only the first appears.
Did anyone experience the same thing ?