Same. Was working on 12.0. 12.2.1 starting having issues.
I have Libreelec on a ASUS NUC connected to port 1 of my tuner, then port 2 (eARC) of an LG. I set the "Connected to HDMI Device" option to "Amplifier / AVR device" and everything works, but on next reboot it gets reset to "TV" and subsequent reboots then try to change the TV's HDMI port to port 1.
It will also try to change the port on the TV to 1 whenever I start to play a video, so I have to change the setting back every time it starts up.
I've exactly the same issue with my Yamaha receiver and 12.2.1. The remote works once with the setting "Amplifier / AVR device" but after reboot it is reset to "TV" and the remote won't work anymore.
I've stopped kodi and removed the CEC XML config file, rebooted and configured the CEC adapter again. But still, after the next reboot it's "TV" again and the remote is not working until I switch the setting back with a USB-Keyword. Very annoying 