Thanks for reaching out. We’re aware of this issue which some users are encountering at present. This continuous loading screen can occur in situations where a users site isn’t yet fully approved for ads to be served from the AdSense network. You’ll find out more below:
https://github.com/google/site-kit-wp/issues/2812
Feel free to subscribe to the GitHub issue for updates, while I’ll also let you know here once the Site Kit notice that appears for not fully approved AdSense accounts is updated.
Note also that the Site Kit placed AdSense code does exist on your site, so ads will appear once your AdSense account status changes. You can check both your AdSense account and site status by accessing the AdSense platform, or checking for any emails sent from the AdSense team.