Suppress email to WP user doesn’t work

Under WordPress User Notification, I have the option to “Suppress the email to the WordPress user” checked. However the site is still producing emails to people saying “This notice confirms that your email address on [site name] was changed to name@example.com. If you did not change your email, please contact the Site Administrator.” This happens when we are merging duplicate contacts that have different emails. It seems like this “suppress” option isn’t working as expected.