I'll look into that, user preferences update happens as a deferred update (it's executed as a last thing during page request). Same happens with the Beta switch. I think that can happen when prod is bit overloaded, and server renders you a new page, but the properties update didn't finish yet. Thats why it renders as "off" state (because switching to ON is still in progress).
I'll update the code to update the database before it returns any content to the user.