Density became worse after refinement in Relion using map and particle from cryosparc

Hi, everyone! I noticed that my refinement job in Relion came out with unexpected result using the map and particles from cryoSPARC. My workflow is 1). export particles and volume to relion, 2). run 3D classification in relion(k=1, T=12),3). run 3D refine using the volume and poses from step 2. It is quite strange that the map after 3D classification was normal but became worse after 3D refine. I have added – boxsize 256 when converting .cs file to .star file. Any idea about that?