Windows can only handle 15 overlays.
Bring up the registry (regedit.exe) and navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers
Delete unwanted overlays until there are only 15 left. In my case, I have DropBox also. I simply deleted DropboxExt6 through 10.
Reboot your computer.
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