Closing and reopening Settings seems to be the missed requirement. I'd disagree with the original assertion that a pro tester would find this in five minutes. The steps to repro are not nearly as simple as originally implied. In fact, they are narrow enough that I'm willing to forgive Apple missing it. (Not fixing it, OTOH, after it's been reported...)
Yup, I've been following along and I also finally got the bugged one by: reopening Change Wallpaper after having closed it with a custom color being selected; and then clicking "custom color".
In a way it's a perfect little example of how a bug can seem obscure to some (most) users/developers but seem glaring and unacceptable to a few (the few who happen to use the relevant feature a lot).
If some engineer at Apple ever gets to fixing this, that would make an exceptional story! Really interesting WHY these circumstances exactly lead to the bugged popup, I can't even imagine what's going wrong there.
