I recently converted my Samsung Chromebook Pro to dual boot Chrome OS and Xubuntu 18.04 with budgie desktop. The screen rotation lock applet appeared to work momentarily, but subsequently screen went upside down again and lock applet no longer appeared to do anything. In fact, screen started rotating almost at random. I used the following commands to correct and disable screen rotation.
Reset screen upright: xrandr -o normal
Stop screen rotation: sudo systemctl stop iio-sensor-proxy.service
Disable screen rotation: sudo systemctl disable iio-sensor-proxy.service
Of course, now the screen cannot rotate, so I am interested in a fix if one exists, but at least screen is upright for laptop mode, which is what I use 99% of the time. I can boot into Chrome OS for the rare occasion I want tablet mode.