After hours of trying every setting possible, I finally figured out what caused my imported Alembic meshes to appear distorted.
My mesh was very small, and apparently there’s this setting called ‘compressed position precision’ under ‘geometry cache’. And this basically simplified all the vertices’ position to the nearest grid-like position.
So, either scale up your Alembic when exporting. Or lower this compressed position precision value to the lowest it can go.
Not sure if this is the exact same issue you have, but it’s worth considering!