Parent Theme Versioning

Hey there,

The following stylesheet enqueue function for child themes is not working as intended. It seems the filemtime function is getting stuck and isn't updating upon file change. The end result is that the child stylesheet changes never show up unless you manually set the version parameter to false in the GeneratePress parent theme. Any idea whats going on?

// Add the child theme CSS if child theme is active.
if ( is_child_theme() )
	wp_enqueue_style( 'generate-child', get_stylesheet_uri(), true, filemtime( get_stylesheet_directory() . '/style.css' ), 'all' );