The component core-loading expects to receive a boolean in the hideUntil input, but the iframe-viewer page is passing a string (the URL). In the ngOnInit function we don't check the type so it works, but if the url is loaded after the ngOnInit function has run then the CSS classes aren't applied as they should.

We should evaluate if we want to make the input more generic (not just booleans) or we want to fix all the places that are not sending a boolean right now.