MRSS - Display poster/background image on audio-only feed

Hi Omega 1, 
It looks like https://github.com/rokudev/feed-specifications/blob/master/mrss-feed-specification.md.
One thing that I have found is that Roku Direct Publisher does not like images unless they are very specific in size, and if your code is right and your image is wrong, then you might as well just hang it up. 
To quote from that document :
media:thumbnail

Required
The thumbnail is used within your application and in the search results. The image size must be 800x450 (width x height) or larger, with a 16x9 aspect ratio. Supported formats are JPG or PNG.
Flag(s):
Flag Required Description
url Required The URL of the thumbnail

So if the image is not at least 800x450 with an aspect ration of 16x9 it will not display.   I don't know that is the issue but I do know that image sizes were a big pain point when I was trying to put up my first channel. 

Is this a background image when the item is playing, or is this a background image on the main screen of the channel?  I think there are limitations on DP for main page background images. (But I am no expert, so someone else will know better)

Good luck, 
Tim