I found quite unfriendly the behavior that overwrites the official version of a mockup when you promote another mockup as the official one.
My expectation was that it would simply take the current official version and switch it to an alternate version instead. Simple as that. It would make so much sense!
Otherwise, change the word “Promote”, because it does not say that it will delete the current official mockup. When someone gets promoted at a company, it doesn’t mean the other employee gets fired.