Default [Q] Rotation Misfanction

Hi, my I9100 when the phone is set to auto-rotate, and is in landscape mode, it will not return into portrait mode. Not even if i set it to no auto-rotation. It runs KitKat (Beanstalk) and even if i manage to get it to portrait, the apps that were viewed in landscape will remain in landscape.
Every tme the only solution is to reboot.
Its defently not a hardware issue, but i have noticed while using apps that show the orientation of the phone such as Bubble level, that the phone doesnt detect when it is faced bottom side, up.
Please help