sorry if you've read this before…

How does one properly export deforming geometry from maya and import it into houdini in such a way that deformation motion blur works correctly with a 0.5 shutter interval?
Maya's alembic export settings: step size = 1, and FrameRelativeSample = 0.0 and 0.5
houdini is set up with camera shutter=0.5 geo_motionsamples=2

I'm getting intermittent frames with no motion blur at all, and, motion blur is as though shutter=1.0.

I know I can work around the issue by lerping the geometry sampled at the integer frame values, but I was hoping I wouldn't have to.

try adding a Timeblend SOP after your alembic SOP