The Swifty.js script adds an event listener for DOMContentLoaded, but the event has already fired by the time the script executes, preventing the Swifty setup code from running and the beacon HTML from being added to the page.

The issue can be resolved locally by modifying the script to check document.readyState. If document.readyState === 'loading', the event listener is added; otherwise, the initialization function is executed immediately.