Dropbox uses icon file overlay to show file sync status in File Explorer in Windows 10. Windows has a limit of just 15 overlay icons and different applications push other appliations out of the top 15 slots - this is often why some Windows users have missing overlay.
OneDrive has moved to using a separate column in File Explorer as shown in the following example. This also means you can order by status.
It would be great if Dropbox could adopt a similar solution.