Ridiculous that they imply throughout that they have a (mysteriously silent) Level 3 support or engineering team working on the issue for almost that entire time. Would be amazing if that's actually true and it turns out they discovered some huge underlying issue with the system from the user logs that they've actually had a team working on... but I'm sure it isn't. For a start if an issue like that was being worked…
I won't say much publicly, but if this is the issue I think it is (customer has a huge number of files, and is trying to sync it with a 32-bit client, and hitting memory issues), we are aware of the issue, and are definitely working on it.
It's a tricky thing to solve in any sync client - for example, Dropbox has a cap around 300,000 files (I believe this customer had 700,000 files?):
> https://www.dropbox.com/help/space/file-storage-limit
Note: The performance of the Dropbox application may start to decline when you store above 300,000 files.
Other clients may have similar limits. I'll see if I can find our docs on it.
Disclaimer: I work for Google.