I've discovered RStudio Cloud this week and have been working with it for the past three days. It is awesome, thanks for the amazing tool.
I believe I might have done something wrong in terms of memory usage because I am not being able to load my project since this afternoon (https://rstudio.cloud/spaces/40939/project/746449). I keep getting the same "Opening Project" screen.
I look a look, and I didn't notice any problems in the logs for that project. We've had reports of users being unable to open projects due to a bug where the browser is deleting authentication cookies (particularly on Google Chrome). I would be curious if you logged out of RStudio Cloud, and logged back in, and then try and open the project again.