I have the problem when I upload media from activity stream in MS Edge (version Microsoft Edge 38.14393.1066.0 Microsoft EdgeHTML 14.14393 and Microsoft Edge 25.10586.672.0). I got the page “Are you sure you want to do this? Please try again.” “Please try again” link return you to the previous Activity stream page. The media was uploaded to the site and I can see it through member Media gallery and Media Library. All other browsers (Firefox and Chrome) work as expected. I am getting the same result in your demo web site http://demo.rtmedia.io. I found several posts with the same problem in this community, but no solution for it. Any suggestions?