As @AnnaFless said, the first candidate for this sort of problems is websockets, which do work with IE11.
I have looked deeper into the issue and I can confirm that IE11 has been experiencing some problems with our online post-processing solution.
While Internet Explorer is not officially supported by our platform, we always try to ensure compatibility with a broad selection of browsers, but some issues like this might arise from time to time.
We are investigating the cause and will address this problem so that IE11 works again for the post-processor.
We will keep you updated on the progress.