Shipping question

[muchosportscards]

Good morning to all. I recently set up the "flat shipping rule" on eBay as a seller to where buyers can add cards to the eBay cart, checkout and automatically the posted $2 for shipping per card is automatically deducted for each card after the first. However it doesn't look like the deal worked with the last buyer. Wondering if anyone has had experience using this and or could there be a kink in the system if people are buying using apps? Below is a snap shot of details of what I have set up in my eBay selling preferences. Thanks for your time and have a good day.

IMG_9412.PNG ‏199 KB