Blocked by Content Security Policy
The short answer
Your site has a Content Security Policy that blocks scripts from domains it does not know, and ours is one of them. Add *.elfsight.com to the allowed script sources and the widget loads.
The console message begins *Refused to load the script because it violates the following Content Security Policy directive*.
Confirming it is CSP
Open the browser console — F12 on Windows, Cmd+Option+J on a Mac — and reload. A CSP block produces a red message naming the directive that rejected the script, usually script-src. If you see that, this is your problem and nothing else is.
The fix
Add our domain to the relevant directives in your policy. Where the policy lives depends on your stack: a Content-Security-Policy header from the server, a meta tag in the page head, or a security plugin. Add *.elfsight.com to script-src, and to connect-src and img-src if those are also restricted.
If you do not control the policy
On managed hosting or behind a corporate proxy, the policy may not be yours to change. Whoever administers it needs the domain added — that is the whole request, and it is a routine one.