Under Settings/General Management/Physical Keyboard, confirm that "Book Cover Keyboard (EF-DX915)" is listed. If it is not, I suspect there is a connectivity issue. Try disconnecting and reconnecting to see if that helps. I had a similar issue with the slim keyboard and that was the problem. Good luck!
PS. There appears to be three brightness settings for the backlight. After pressing, the Fn indicator will remain lit and when you hit F12, backlight will be low (1st press) medium brightness (2nd press) and max brightness (3rd press). Note there is a time out. The backlight will turn off automatically if there is not typing activitiy or movement on the trackpad.
PPS: Press and hold the Fn key for about four seconds to turn function indicator on and off. Make sure the Fn indicator is on before hitting F12. Press and hold Fn key to turn off the indicator. 😊
