Probably I am the first one to encounter this issue.
It is 3.0.0-preview, just create 2 Quad objects, assign the same material with shader “LightweightPipeline/Standard (Simple Lighting)”, with Enable GPU Instancing on, the quads are not rendered on the device.
Legacy pipeline with Mobile/Diffuse is good.
Can you please log a bug so this doesn’t get lost 
With un-modified 3.0.0-preview, the rendering is good if pipeline asset’s Vertex Lighting is on.
In Lighting.hlsl > LightweightFragmentBlinnPhong(), if inputData.bakedGI is used, you may encounter this issue. inputData.bakedGI is not initialized in MixRealtimeAndBakedGI() if the geometry is fully real-time (not _MIXED_LIGHTING_SUBTRACTIVE).