The SCORA app runs in full screen mode, making maximum usage of the screen. To switch back to the main Android screen, or other apps, one needs to first make the system bar visible by swiping from the bottom of the screen upwards.
This swiping up to make the system bar visible does not work on the Maestro screens. In order to exit the SCORA application, or to move to another one, one must use a workaround.
To make the system bar visible, one can either enter the annotation mode by double tapping on music content. If no content was opened yet, one can open the detailed settings screen by tapping on the cogwheel button in the upper right corner of the viewer app.
Doing either of this makes the system bar visible with all the normal buttons.
We will fix this issue in a future release.