Are you missing the green (or red and blue) icon overlays that show the OneDrive for Business status on folders and files? Then, you might want to try following these steps.
How To Fix It
1. Head over the following link: https://support.microsoft.com/en-us/kb/3079213
2. Scroll down and download the easy fix tool (blue Download button).
3. Run it on your Windows PC.
4. Select 'Yes' to restore the icon overlays.
5. Once completed, you can close the tool.
6. Hey Presto! You should see the overlays on the icons again.
If the above steps don't work, check out Microsoft's article for more advanced steps to fix this issue: