due to some changes in the Amazon API, you could discover some problems on your website where the Amazon products should show up. I am working on a new update of AmazonSimpleAdmin to support the new API. I will hopefully release it within the next couple of days. This new version also will support the Amazon stores Italy, Spain and China and comes along with some other bugfixes and a solution to keep your custom templates when updating. But for this next update you still have to backup your templates once again.
If you have any questions, please feel free to contact me.