channel.link Validation Error, Support for Dark Mode

I’ve installed and configured my staging site with the plugin, but when I go to the SmartNews Feed Validator, I see an error:

Result Invalid
Error Messages
channel.link is required

I do not see any results for this in the SmartNews Support Forum, and am not sure how to proceed. If this is an issue related to the staging site being on a subdomain, let me know and I can test another method.

A screenshot of this error can be found here: https://imgur.com/V93G7m3

Also, will there be upcoming plugin support for the <snf:darkModeLogo> option? It was announced for https://publishers.smartnews.com/hc/en-us/articles/360036526213.

Thanks in advance!