When ExpressionEngine calls your class to execute an action, it passes a constructor argument of 0
In /system/expressionengine/libraries/Actions.php, you will find this code around line 185
// Instantiate the class/method
$ACT = new $class(0);
Not sure why this is done, but if your class takes a constructor argument (like mine does) you may find yourself scratching your head at why it won’t load when called from an action.

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