[Groom] Character groom hair degenerate after selecting binding asset

Broblem: Make a blueprint of a skeletal mesh, then add groom asset. The hair quiality worsen when its binding asset is set.

Step to reproduce the problem:
S1. So I am simply importing mixamo’s Y-bot as a skeletal mesh and a simple alembic hair strand made with houdini


You see it has 50000 hair strands

S2.Creating an actor blueprint and add the Y-bot’s skeletal mesh

S3.Import and add the groom asset from houdini’s alembic hair strand file


Everything looks good now.
And then create the binding asset for the groom asset.

S4.Select this binding asset in the actor blueprint.
Then the problem shows up: after selecting binding asset, there are less hair strands, and looks like the hair strands have less divisions