I thought there might be a request size limit, since there's an nginx in front of Anarki. But then I tried connecting directly to the Anarki web port and got the same result.
Here's a 822K file which I just confirmed fails to be uploaded:
Sorry for leaving you hanging here.... I'm not really in the practice of running news.arc, and when I asked for a file to use for testing it's because I thought maybe someone else would pick up my slack. XD