I am not a big used of Google Drive. It is a good service and it mostly does what one may need from a suite of productivity apps… but for some reason I only use it in very limited cases.
So, no surprise that I had not noticed that the synching between the cloud version of my documents and those in my mac had gone pear shaped. I tried logging out of Drive but that did not help. I attempted forcing the synch by making changed in both the cloud version and the Mac, but same result. 
I managed to sort it out in the end and here is what I did:
- Exit the Drive application
- Navigate to the Application Support folder and look for the Google folderYou may need to find the hidden Library folder
- In Finder look for the Go menu and press Option + Cmd to reveal the hidden folder
- Once there look for the “Application Support”
- Alternatively you can press Cmd + Shift + G and go to “~/Library/Application Support/Google”
- Delete the Drive fokder
- Start the Drive application
Et voilà