When testing several devices (Lumia 520, 620, 920, 1520), the 920 was the only device which failed to properly render a Qt Quick scene with the stencil/depth buffer enabled. Only the background color of the window was shown.
There is probably a capability check which would reveal the problem. If no errors are found within the OpenGL state, then we may need to blacklist the Adreno 225 to exclude the depth/stencil buffer. It is the oldest GPU used in this range of devices, with most devices having either Adreno 305 or 330 chips.