[phenixbb] map to model fsc did not start from 1

Dear Phenix developer, I have a question regarding the map to model fsc. I have a filament map and a model with arbitrary copy of the protomer ( I built them in Chimera), then I used the filament model to refine against my map. But I encountered an issue is that the reported FSC (map to model) did not start from 1 but rather 0.8. I am wondering if there is anyway to fix it. Also, in the case of a filament, how do I use NCS operator to refine rather than manual building the filament model? I tried specifying NCS with helical symmetry, but it did not work. Best, Yangqi