If in your browser console, you can see errors related to Content Security Policies
like:
"Refused to load the script 'https://assetscdn.stackla.com/media/js/widget/xxx because it violates the following Content Security Policy directive: ..."
please ensure that you add that Nosto domain to your CSP directive.
In the example above you would need to add "https://assetscdn.stackla.com" to your CSP directive.