User default settings does not update or inform correctly

I visited the new User Default Settings screen and changed the default from text to html.
Then I pressed on "Apply" and received the message:

Change Users Default Email Preference
Are you sure you would like to change all users who currently receive 'text' email to receive 'html' email instead? A total of 12 users will be affected. Note that this change cannot be undone, and should only be performed if you really know what you are doing.
I'm not sure what 12 users it thinks have the text setting (there should be none since my preferences-default.xml was always set to html), but I went ahead with the update. However, if I perform the update again, I get the same message again.
Which means it never really updated all 12 text users to html, or (the more likely scenario), there aren't really 12 users set to text in the first place.