SOLVED: 3D Touching Control Center crashes Springboard. To fix, turn off "Speak Screen" under Accessibility>Speech. Restart phone for the setting to go into effect.
It's unbelievable, but this one option has caused various problems going back to iOS10. In iOS10, if Speak Screen was ON, it would cause only the most recent 20 or so notifications to show up in the Notification Center; then the NC would scroll endlessly but all you'd see would be a blank screen. Try it, just don't forget to restart before the thing goes into effect.
In iOS 11 beta4 it would cause the AppSwitcher to jump to the left on opening. In iOS 11 beta 5 it was finally fixed--I reported it numerous times before. In beta 6 it causes the crash of springboard on 3D touch of CC buttons.