So I’m seeing some strange things on my side. The validator is sometimes indicating a timeout connecting to your site (although it loads fine for me using a browser or curl). Another tool I’m using is indicating an HTTP 406 “Not acceptable” error. When the page is fetched successfully by the validator, I get the “no tags found” error you’re reporting.
Can I ask you to temporarily try disabling the W3 Total Cache plugin? I wonder if something weird is happening there.
The other thing I see in the page is that you’re trying to use a summary large image card, but there’s no image tag there. Even when we get the issue with the “missing” tags with the validator sorted out, we need to fix that as well.