I noticed several months ago that the Amazon Mobile Ads iOS SDK was causing my iOS app to lock up. The errors had to do with the API accessing data on the wrong thread. I was in a rush to get the app published, and I knew I couldn't include the Amazon Mobile Ads SDK if it was going to cause the app to hang, so I removed it. I cannot recreate the errors to post them here, but I noticed that the SDK has not been updated since the time I was getting these errors. My question for Amazon is: did you happen to have threading errors reported by anyone else in the last couple of months, and have they been fixed? If not in the SDK, then maybe on your server's end?