Hi @kcsmalley
If you are using a Custom Feed URL using the directions found in our KB Article:
https://kb.wprssaggregator.com/article/194-creating-a-custom-rss-feed-of-imported-feed-items, this will work if you are using the Core Plugin.
This feature does not work when using the Feed to Post add-on and importing the feed items as Posts, or any other Custom Post Type since those would then form part of your website’s default RSS feeds.
If you are using our premium add-ons and need support, please only contact us via a premium support ticket on this link: http://www.wprssaggregator.com/contact/
That being said, you will need to add the custom feed URL back into your Feed Source settings and make it a Feed Source URL.
Once it’s a Feed Source, add the shortcode to a page and it should appear.
If you are having trouble with this still after following the directions in the article, I would suggest testing for theme/plugin conflicts as detailed here:
https://kb.wprssaggregator.com/category/83-plugin-theme-conflicts
Let me know if that helps!