Problem:

Amazon Prime video displays incorrect aspect ratio on TV.

Solution:

Check your 2016 Smart TV's firmware version. If it's running firmware 1233, this may cause Amazon Prime videos to display in an incorrect aspect ratio, stretching the image to fill the screen without maintaining proper proportions (with black bars above and below).

To resolve this issue, update your TV's firmware to version 1240.0 or higher. This can be done directly from your TV by navigating to Settings > Support > Software Update > Update Now.

Allow several minutes for the update to complete, and avoid turning off the TV during this process. The TV will automatically restart once the update is finished.