Internet Explorer breaks affiliate attribution

Hi,

I just discovered that Internet explorer also breaks affiliate attribution. Details below:

A client is having some severe problems with the affiliates plugin. When their clients use Internet Explorer browser, the affiliate leads get attributed to direct or some other affiliate. I have the following setup:

WordPress 4.2.2
Affiliates Pro: 2.9
Internet explorer 11 (the latest version)
Affiliates Contact Form 7 add-on: 3.3.0

It works fine in chrome and IE, but not in Firefox. Any ideas?

Thank,

Nathan