Go back again to the Files page in the utility and click "Open in File Explorer." The folder that opens is the one that has been getting updates. In the address bar click UI and you will see this folder and at least one other custom folder name.
If you have not configured your UI heavily, the cleanest thing would be to log out of the game and close the utility. Drag and drop both custom folders (red arrows) onto the desktop. Then reopen the utility and let it do a fresh install.
If you have done a lot of custom configurations that you'd rather not redo, post again and I'll show you how to copy those into the new installation.
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