Overview

Windows has a limit of total icon overlay handler can support "an image list can have up to 15 overlay masks".

If you have many applications that install icon overlay handler (such as Dropbox, Google Drive, OneDrive and etc), some icon overlay handler may be pushed out from your cloud drive mapping.

Details

Finding existing overlay icons in the Registry

You can find existing handler list on the Registry:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers

and

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers

How to prioritize Client icons?

1. Remove from the Registry the handler you no longer need or uninstall its respective Application.
2. Change the order on the list, putting in the top the ones you most use. To achieve that, you can rename the icon overlays registry (right-click -> Rename) and insert a few empty spaces at the beginning of the name.

This way, they'll show on the top of the icon overlay list.

After making the changes in the registry, restart the explorer task for the changes to take effect.