I had an IAP subscription running in a live app and I decided to add a promotional offer for a discounted price for one month with a start date of sep 28 and an end date of dec 31. I set this up on Sep 27 for our two live apps. But I found that subscriptions failed in both apps afterwards. After I set it up i went to test on September 28 and i saw that it had become impossible to subscribe. When I click the subscribe button in the app, the "Select Subscription" appears from Amazon. After I click that button i get a blank screen and return to the screen with the original app subscribe button. I freed up storage space (which seems to help the flaky subscription api), I restarted and I tried on different devices.
On the 2nd generation FireTV I actually succeeded in subscribing with the promotional price for one of the apps, but not the other. But then when I log into another device using the same amazon account, the subscription is not available on the same app.