Biggest issue for performance marketers on mobile?

What would you say is the biggest problem on mobile platforms for performance marketers? I'm looking to create a software solution for that market and would love to hear if you have any issues that I can help fix.

Tracking!

Unlike the desktop, a significant amount of sales don't get attributed on the mobile. There are several reasons why:

• User ends up downloading the merchant's app (which they promote as the page loads) and the sale is lost or not attributed to the source. Very few merchants provide affiliates with post back information.
  
  
• Users saves the product to purchase later from another device (desktop or tablet). Affiliates again don't get attributed for the sale.

Traction is without a doubt the biggest issue on mobile and a problem yet to be solved.