[chimerax-users] How to activate the Extract button in Segment Map function?

Dear ChimeraX, I tried to use Segment Map to remove some portions of the cryoEM map, and extract the selected portion, but the extract button remains shaded. The only tab in the "other tools" row that appears to be activated is "Fit". I have the most recent version of ChimeraX installaed(Sept 19). Could you give me some hints how to activate the extract in "Other tools" under the "Shortcut options" in "Segment Map"? Thanks! Bo