Force Single Instance works only when launching app file but you can still open new instance via Contents/MacOS/appname

1. What happened

Force Single Instance works only when launching appname.app file but you can still open new instance via appnema.app/Contents/MacOS/appname

2. How we can reproduce it using the example you attached

1. Set "Force Single Instance" in Player Settings for Standalone.
2. Build & Run the app.
3. If you click on app again - it will show current running window as expected.
4. If you go to and run appname.app/Content/MacOS/appname it will open new instance.

RESOLUTION: By design: appname.app/Content/MacOS/appname is not end-user visible path, so opening it directly is not supported.