Interesting. I changed my wallpaper to a slideshow of some solid color PNGs I made, made sure I wasn't in Tablet Mode, and made sure both "Automatically pick an accent color from my background" and "Show color on Start, taskbar, and action center" were set in Settings::Personalization::Colors. I then opened up the Performance Options. On my desktop system I do not find that any combination of the Performance Options settings have any effect upon this: I find that in all cases when the wallpaper updates the taskbar color updates as well.

Is this happening to anybody here on desktop computers? Is this happening for anybody here only for Surface 3 (Pros), or is there any other class of afflicted computer?

Interesting data so far. I don't see this myself right now, but perhaps I'm missing something.