Amazon has changed affiliate rules for free books:
YOU WILL NOT BE ELIGIBLE TO EARN ANY ADVERTISING FEES DURING ANY MONTH IN WHICH YOU MEET THE FOLLOWING CONDITIONS:
(a) 20,000 or more free Kindle eBooks are ordered and downloaded during Sessions attributed to your Special Links; and
(b) At least 80% of all Kindle eBooks ordered and downloaded during Sessions attributed to your Special Links are free Kindle eBooks
I don’t think I ever have met the first criteria, but I assume that I do the 2nd. But I didn’t think Amazon was paying me anything for the free books anyway, so I am not sure I understand the issue. I’m also wondering if the use of the conjunction ‘and’ instead of ‘or’ between the two clauses doesn’t mean this has nothing to do with me.