It seems it doesn't be correctly saved, if I use command $ with the same app, it is correctly saved
In the json exported, it appears as cmd + ] when using command + $ :
73 "appBundleURL" : "file:\/\/\/Applications\/Spotify.app\/",
74 "appDisplayName" : "Spotify.app",
75 "shortcut" : "cmd+]"
and as a blank shortcut when exporting with command + @ setted:
73 "appBundleURL" : "file:\/\/\/Applications\/Spotify.app\/",
74 "appDisplayName" : "Spotify.app",
75 "shortcut" : ""
Maybe an issue with my french keyboard layout ?