I used Android Studio's Asset Studio to generate TV banners:

Everything looks great in Asset Studio, but the generated adaptive-icon crops the image so much that it is unusable:

Here is what it looks like on Android TV:

Could anyone shed some light on how to remove the cropping?
Since no one has answered the question since it was posted 9 months ago, let me try to answer it with my own solution.
Android Studio's Asset Studio to generates several file one of which is ic_banner.xml under directory mipmap-anydpi-v26:
It shows the cropped image. I have modified it as follows:
Now, the icon looks just like other TV app icons. I got the hint from this post.