I decided to try to run Cloud9 on an ARM server ("Graviton"). I created an EC2 t4g.medium
instance and a key, made sure I could SSH into it as expected (no problem), and then created a Cloud9 SSH environment. It mostly seemed to install without issue aside from a mild complaint about Sqlite. When I opened the IDE, it was perfect. Terminals worked as expected, files saved, autoformatter autoformatted and the world was good.
Every subsequent time I have opened the IDE, however, it has just given me a loading spinner. After a lot of Googling I noted that this pattern has been seen before. I tried installing tmux, but that had no effect. See screenshot: