Mobx get latest value of a property

I have the following code inside a mobx store:

  order: string = "";
  
  processOrder = async (order: string) => {
    ...
    console.log(order, "--", this.order);
   ...
  };

and the console.log is allways outputing -- ,and it looks like this is the output is the same even if I change the start value ,but i have no idea how can i get the actual value of that property.