I have two issue with my LG LM640S television when using it with one of the latest KODI 18 testbuilds. I tried and the same issue happens on the stable Libreelec and I can confirm that everything was fine with libcec 3 in older libreelec/openelec releases.
My config:
TV: LG LM640S
HDMI 1: RPI2 with KODI with testbuilds from LibreELEC Testbuilds for RaspberryPi (Kodi 18.0)
Kodi (18.0-ALPHA1 Git:78cce57)
LibreELEC (Milhouse) - Version: devel-20170407212644-#0407-gf3caa55 [Build #0407] 9.0, kernel: Linux ARM 32-bit version 4.10.8
CEC adapter settings: Dropbox - IMG_5327.JPG
ISSUE 1
- RPI is always switched on from a wall adapter
When we are turning on the TV, it switch to the RPI as an active source. It does not matter if the last input was tv or not.
Same happens if tv is turned on and I restart the RPI or plug out and then plugin in RPI.
LOG: Dropbox - kodi.log2
The log snapshot were made just after the tv auto switched the source to RPI, so the CEC log is in the last minute.
ISSUE 2
When I pause a video with tv remote, the video starts to play after 10-20 seconds. When logging disabled, this issue comes almost every time. When logging enabled, it happens 1 in 5 times. Very annoying 
Part of the log, where I pause the video on CEC and when it start to play: 18:46:40.769 T:1603687328 DEBUG: CecLogMessage - >> 01:44:46 18:46:40.769 T:1 - Pastebin.com
Full LOG: Dropbox - kodi.log3
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I opened a ticket at github for libcec, but maybe it will be a solution inside libreelec. Related ticket: LG TV - issues with LIBCEC 4 (Source switch when TV switched on/auto play paused video) · Issue #344 · Pulse-Eight/libcec · GitHub
