You have set a new key building in the Grease pencil (global) group. This group basically means that this hotkeys is used in Grease pencil globally - in all tools and in all Grease pencil modes (paint, edit, sculpt) but not in object mode. Thats means that to launch this command you have to be in one of Grease pencil modes, but you are in Object mode, so that this command is ignored.
So that you have to use suitable keymap group.
3D View ⇾ 3D View (Global) is good for that, key building from this group will be executed in every mode including Grease pencil edit mode or pencil sculpt mode
3D View ⇾ Object Mode ⇾ Object Mode (Global) also is good, but the difference that it will be executed only in object mode, in
Grease pencil edit mode or pencil sculpt mode it will not work.