This issue came up in these forums back in Nov '15. But just today I turned on a computer that had been off for a week and instead of updating the files on that computer insync nuked all the new files! This has got to be a bug - it is definitely a pain.
@Richard_Ketchersid thanks for reporting this. Please send your log files to support@insynchq.com so our engineers can troubleshoot How to find the log files