Insync made my files disappear

I use Insync with Lubuntu 14.04 LTS. I am becoming increasingly concerned about the safety of my files when using insync. On 26 August after syncing with a second computer (not my main one), I found one very important folder had no files in it. I believed Insync was supposed to keep the latest version of folders and files. I believe in this case it did not do that. This is the second time this has happened. Less importantly, but equally worryingly, yesterday 28 August, the app window feed told me I had just modified two files which actually I had not modified for several days. Please can a technician help me understand what has happened?
Thank you.

@rdh61 Please send your logs to How to find the log files.