Numeric fields not showing aggregations

Hi,
I am using json inline datasource. I see an issue related to numeric field if contains null value in first object in an array. it's considering a text column and not showing numeric aggregations(sum, max, min etc...) please try to load below data and pull Quantity into measures section and observe the functions.

var jsonData = [
  {
   "Color":"green",
   "M":"September",
   "W":"Wed",
   "Country" : "Canada",
   "State" : "Ontario",
   "City" : "Toronto",
   "Price":174,
   "Quantity":null
  },
  {
   "Color":"red",
   "M":"March",
   "W":"Mon",
   "Country" : "USA",
   "State" : "California",
   "City" : "Los Angeles",
   "Price":1664,
   "Quantity":19
  }]

 
Thanks & Regards,
Sunilkumar.V