Hi patrice58,
not too long ago we added an option to lock the screen rotation to the profile settings. In Emergency Mode, the rotation is by default locked (because then the gyro can stay off, which will save a tiny bit of battery too), in Optimized it's by default as you had it before installing Battery Saver. When you plug in your charger, the profile switches back to Optimized so it enables the screen rotation again.
If you want to change this behavior, open the desired profile, open Advanced Settings and check the Screen Rotation switch.
Ondra