There are no changes in the afterSave method

[alexey-bro]

After the model is saved in the afterSave method, the attributes of the object are old and $changedAttributes is also empty.

public function afterSave($insert, $changedAttributes)
{
var_dump($this->depth); //old value
var_dump($changedAttributes) //empty
}

[ricksmort]

Had similar issue myself...
PHP 5
$old_title = null; $old_title = (empty($changedAttributes['title']) ? $new_title : $changedAttributes['title']);
PHP 7+
$old_title = $changedAttributes['title'] ?? null;