I can confirm this issue after updating Debian Testing on a recent ThinkPad E560 with Intel graphics. The screen doesn't seem to be recognised in gnome at all. The "Displays" section in the control center only says "Bildschirminformationen konnten nicht ausgelesen werden" (Could not get screen information). Interestingly the system uses german locales, like the original poster's (?), too, in case that might matter.
And yes: This is with mutter 3.20.3-2 Please let me know if you need some additional informations.
