iOS simulator: double click home button does not work sometimes

Enable this setting in the simulator hardware settings.

Hardware > Keyboard > Send Keyboard Shortcuts to Device

Command + Shift + H + H will no longer do anything BUT double tapping the home button on the simulator will start working as expected.

I have this problem too when I want to close my app. So, I use command line instead:

xcrun simctl list | grep Booted

then copy simulator ID, and run this command to close app

xcrun simctl terminate <simulator ID> <your app bundle ID>

... or if you have only one simulator running, just type booted:

xcrun simctl terminate booted <your app bundle ID>