Amazon Cloud Drive spontaneously deletes files

I have a Ready Nas 202 here at my office and a Ready Nas 102 at home, both running 6.6.0.

Each box has a share which syncs with my Amazon Cloud Drive.  So effectively, I have one data set in two locations.  Both locations should mirror each other via the sync.  This serves the same purpose as a VPN, without the connection issues.  I'm only on one box at any given point in time (I'm the only user).  The box here at the office backs up to an external USB drive overnight.

This works fine, but I am running into a serious problem.  When I am working on a document and make numerous saves and edits and saves etc., after I make the last save it spontaneously dissappears from the Ready Nas boxes and ends up in the Amazon Cloud Drive deleted folder.  If I am fortunate enough to notice, I can log into Amazon, go to the deleted folder, and restore.

This most typically occurs with Excel spreadsheets but I've seen it with MS Word docs and also pdf's.  But its a consistent problem with Excel sheets.

I opended a ticket with Amazon today, but has anyone encounter this problem or have other ideas?