Ember Promise chain not returning sum

I am working with Ember Data and trying to create a computed property equal to the sum all products in a store with their respective discounts applied. I am new to promise chaining and I believe that this is an issue with how I am formatting the chain.

export default DS.Model.extend({
title: DS.attr('string'),
storeProducts: DS.hasMany('storeProduct',{async:true}),
totalStoreValue:function(){  
 store.get('storeProducts').then(function(storeProducts){ //async call 1
   return storeProducts.reduce(function(previousValue, storeProduct){ //begin sum
     return storeProduct.get('product').then(function(product){ //async call 2
       let price = product.get('price');
       let discount = storeProduct.get('discount');
       return previousValue + (price * discount);
     });
   },0);
 }).then(function(result){ //
   return result;
 });
}.property('storeProducts.@each.product'),

Any help and suggestions would be appreciated.