Sync icons (green ticks) are missing from OneDrive for Business synced items

To update the registry, follow these steps:

1. Open registry editor.
2. Move to the following folder, and then expand it:

   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerShellIconOverlayIdentifiers
   

3. Rename the following registry keys

   Old folder name	New folder name
   SkyDrivePro1 (ErrorConflict)	<space><space>SkyDrivePro1 (ErrorConflict)
   SkyDrivePro2 (SyncInProgress)	<space><space>SkyDrivePro2 (SyncInProgress)
   SkyDrivePro3 (InSync)	<space><space>SkyDrivePro3 (InSync)

   On the View menu, click Refresh to verify that the renamed keys now appear at the top of the list.

4. Exit Registry Editor, and then restart your computer.
5. Uninstall any other applications that use icon overlays such as DROPBOX

https://support.microsoft.com/en-gb/kb/3079213