Laptop screen with lid closed is configured as the primary display
when booting Tails 3.0 on a docked laptop with an external monitor, Tails consider the laptop screen as primary, even if the laptop is closed and therefore, the screen is off. In Tails 2.* the display was cloned, allowing the user to set it up.
It seems that Debian-live testing (from 12 june) has the same behavior.
it was reported happening on Dell Latitude E6440 and Dell Lattitude E6410