Just a current update to let others know that the lack of auto save is still an issue with Quickbooks Online. A fellow employee just lost an invoice he was working on for 3+ hours.
Thanks to the others who have posted on this thread -- at least we know the invoice loss was not our error, but that doesn't ease the sting of hours of lost work. (FYI: If you lose an new estimate or invoice due to timing out, you will not find it in the audit trail.)
We did go into settings, as suggested, and increase from one to three hours. We're not trusting the setting change though, based on another commenter's experience, and will try to save our work periodically to be on the safe side.
I find it ironic that while typing this Quickbooks discussion board message an autosave notice comes up letting me know my work is being saved periodically. Come on Intuit -- get it together and solve this problem!