Procedural does not render motion blur for primvar.velocities

[xsisupport]

Describe the bug
Render delegate renders motion blur, but procedural (sick, kick) do not.

If I convert the usda file to ass, I can see that the motion keys are exactly the same for each point.
In contrast, the hddebug ass file from Solaris has good motion keys.

To Reproduce
Steps to reproduce the behavior:

1. Extract the attached zip, load the hip file, and render with Direct USD Render.
   or
   kick the attached usd file

particles_mb.zip
usda.zip

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots

Used Software Versions

• Houdini, HtoA

[autodesk-oss-arnold-bot]

Issue synced internally to ARNOLD-14762

[sebastienblor]

Note that, for the fix to work, the attribute needs to be set as "velocities" and not "primvars:velocities"