Hello szheng,
I think that the following is happening:
cameras have checked on coordinates in the Reference pane, but the values are loaded as degrees in Lat/Long/Alt format, whereas the coordinate system in Reference pane settings is selected as some projected coordinate system (certain UTM zone, for example).
You need either to uncheck all cameras before the optimization, or to apply proper selection of the coordinate systems for chunk, cameras and markers in the Reference pane settings dialog.