[WP] BillboardWavingDoublePass - shader unsupported

When I deploy from VS to WP 8.1 I get these messages in debug mode:

WARNING: Shader Unsupported: 'Hidden/TerrainEngine/Details/BillboardWavingDoublePass' - Pass '' shader state not supported

How do I resolve this?

That's builtin Unity shader, probably used by trees, do you see any visual artifacts? If no, then ignore this warning