[Chimera-users] Different center when display coordinates with bonds or ribbon

Dear chimera developers and users, Recently, I met a very strange issue about displaying coordinates in chimera. I found the helices were off-centered with the map, when I open a well refined PDB file and the map it was refined against, and keep an eye on the helices which is automatically displayed by Ribbon. But actually they are will aligned in COOT. And if I hide Ribbon and showed Atoms/Bonds, they were well-aligned. The attached files show the same region with different displaying modes. And I have tried several versions of chimera, the results were the same. Actually, I want to use Ribbon to display these helices. Does anyone know how to fix it? Thanks in advance! Yang