There is a specific setting for the light being on while the screen is on, not sure if there is one for it being off though.
Not sure why it wouldn't work for you. Maybe try this app if you're rooted.
Grab Matlog and grant it root. Then click the overflow (triple dot) menu, press log level and set it to debug. Then, go back into the overflow menu, press file and then record. When you're done, click the save button.
Alternatively, if you don't have root access, you can use the Android Debugging Bridge. adb logcat -f [/path/to/file/on/phone.txt] *:D (the level of logging). Once you press enter, it will begin logging. When you're ready to stop, press Ctrl+C.
get this one (free) https://play.google.com/store/apps/details?id=com.themezilla.pixelui or this one (99 cents and the one that i have) https://play.google.com/store/apps/details?id=com.ciaostudio.pixeliconpack and you never have to complain again.