Hi,
We can reproduce it via this code
<html>
<body>
<h1>
test</h1>
<button onclick='document.getElementById("iframe1").style.display=""'>
ShowIframe</button>
<br />
<div>
<iframe src="large-file-upload.aspx" width="1100" height="700" style="display: none"
id="iframe1"></iframe>
</div>
</body>
</html>
The reason is that the iframe is hidden , and the script in the iframe not works.
We have fixed it, and will provide an update soon.
Regards,
Terry