Thanks Alexey
Sadly the problem has now compounded. I came back to the machine to find that the download was so big that it filled the hard drive and now I get the error 'cannot open archive', presumably because the .zip project file is corrupted. All the files seem to be present in the '.files' folder. How do I now get back into my project?
(I must say, from my tests so far, the way the cloud processing is configured is really problematic)