Because sometimes little things make the difference.
Stuck
Sometimes PhpStorm gets stuck in the middle of an XDebug session and simply refuses to move to the next break point.
It happens often if the process under debugging dies or exits.
My workaround has been, for a while, to reboot either Terminal or PhpStorm but there’s a simpler way: on a Mac cmd + alt + r will make the debug session move to the next break point (Resume program shortcut) and hitting that key combination one or two times while PhpStorm is “stuck” will make it move on and resume its functions normally.