I'm building a custom activity for Journey Builder. When I click on the activity in the Journey canvas the UI (index.html) is grayed out with an infinite SFMC loader.
All network requests in the developer tools show a 200 status. No errors appear in the console, but console.log() statements in my customActivity.js are not displayed either.
The activity’s index.html loads fine when accessed directly in the browser, and the server responds correctly to all endpoint requests.
What could be causing this behavior? How can I debug this further?
