Hi Adam. Happy to share that the issue is resolved now.
None was displayed in: WordPress -> Google site kit plugin-> Setting-> Adsense-> Web Stories Ad Unit -> None
When I clicked on the Edit option present there and selected the Ad unit which I had created for webstories from the dropdown then slot ID was displayed in place of None and ads started running in web stories.
Hope it makes sense and will help others. Thanks for your support.
@joyously Thanks for your reply Joy. But this way duplicate URLs for same post will keep on creating. Will it have any impact on SEO searches.
