ATP does not take into account reserved stock

Hello, our ATP does not take into account reserved stock when it calculates the delivery dates

Example

Item Lead time 10 Days

QTY on Hand                 20

Physical reserved           15

Order reserved               5

Creating new Sales Quote/Order - ATP shows that the stock is on hand and we can ship.

This cannot be the expected behaviour?

(I expect ATP to show delivery date as today plus 10 days (lead time) if no other inbound supply is in ATP time fence, as no stock is available for the new order)

Our version 2012 R2 CU7

Thanks