**System Information**
Operating system: windows 7 64 bit
Graphics card: amd r9 270
**Blender Version**
Broken: 2.80 stable
**Short description of error**
Light path nodes output doesn't have an effect on (true) vector displacement.
**Exact steps for others to reproduce the error**
In the provided .blend, click viewport shading. The cube doesn't move (notice the yellow outline when selected). But Is Camera Ray should input 1 to vector displacement node. All Light Path nodes outputs seem to output 0 when connected in vector displacement.