Blend direction with ArcSphere makes particles disappear

Comes with new ArcSphere integration

Repro steps: 

• Open unity and create a new VFX Graph 
• Create a set positon Arcsphere block in initialize context
• Change the direction composition of the sphere block to "blend"

Expected: Particle's Direction blends

Hapenning: Particles disappear

Errors in console: 

-Shader error in 'New Graph 1] [System] Initialize Particle': 'lerp': no matching 3 parameter intrinsic function; Possible intrinsic functions are: lerp(float [System] Initialize Particle': undeclared identifier 'blendDirection' at kernel CSMain at 1.vfx(106) (on d3d11)

-[New Graph 1] [System] Initialize Particle.compute: Kernel at index (0) is invalid