When using Internet Explorer 11, I have found that when loading multiple files, my website hangs so thought I'd try the demo and see if that works and it doesn't.
If you select multiple files, it hangs trying to load the first one with "1 second remaining", see below screen shot.
I have tried on my win8 IE11, it works fine. can you check your ie document mode? Can you change it to Edge(default) to try again?
I am using Windows 7, IE 11. Where are the document mode settings you mention?
please hit f12 on browser, it will open the setting panel below. you will find the document mode setting.