Having the same problem. Who flagged the OP for this question? It's a legitimate problem, Amazon is NOT syncing correctly. I paid 6$ for this feature and I can't even take advantage of it. May have to contact Google for a refund it does not get fixed soon.
Google will refund you too by the way, just tell them the app is not working as advertised and explain the situation. They have refunded me many times, even on purchases 2+ years old. With some apps, they let me keep the license as well.