I've searched around and seen this problem is quite common, but none of the fixes I've read have resolved the issue: If VR Mode is enabled in the GvrViewerMain prefab, the scene will render as just a black screen.
I've set the Graphics API to OpenGLES2, I've disabled Multithreaded Rendering, I've disabled direct render, yet this continues to be an issue.
This happens both within unity itself and if it is built and run to my phone. Has anybody encountered this problem/do you know of any further steps to take to resolve the issue?