Experienced the same problem as the OP. Downgrading to 4.15.0-43 worked for as well. The only difference is that my laptop is Dell E7450.
To be more specific, With dock and an external screen the system freezes when I close the laptop lid. When booting with the laptop lid is closed, the system does not even get to login screen. With laptop lid open everything works. With laptop not in dock everything works.
Experienced the same problem as the OP. Downgrading to 4.15.0-43 worked for as well. The only difference is that my laptop is Dell E7450.
To be more specific, With dock and an external screen the system freezes when I close the laptop lid. When booting with the laptop lid is closed, the system does not even get to login screen. With laptop lid open everything works. With laptop not in dock everything works.