By default, Sublime Text 4 does not save files automatically. Especially when switching from another editor or IDE like PHPStorm, this can quickly become annoying, if you are used to use automatic saving.
Fortunately, auto-saving can be enabled with a single line in Sublime Text’s user settings:
This line causes (as the name implies) the file to be automatically saved as soon as focus is lost. Examples of this could be switching to another file or to another window.