Any particular reason you feel alternatives like Box or Dropbox are safer?
As stated previously, there are known issues with Google Drive and other software like Scrivener. As you don’t definitively know what caused the data loss and reproduction seems unlikely, eliminating variables seems like the next step.
- verify there aren’t any other processes modifying your vault files (on OS X, use
lsof) - maybe there is an accidental shortcut for the ‘Delete current file’ pallet action
- try running a local vault
- try a different approach for sync and backup (git, dropbox, etc)