I have the same problem. I've just tried again this morning with yesterday's nightly build and its still there, no way to get the TV remote working.
Using a wireless keyboard is fine apart from the other problem - FF & rewind on MP4's is stuffed.
I think its a Kodi not a LibreElec specific problem since I've tried XBian & OSMC with the same result.
I've decided to try the nightly build at weekly intervals to see if things are fixed. AT least I have my Pi3s working well.
Try turning off the TV totally (no power) and let it sit awhile before turning it back on. My Samsung randomly gets CEC 'lock' and just doesn't want to play nicely with the attached Pis until it's sat in the naughty corner for a while.
Little update
Since when do you need a Pulse-Eight adapter for a Raspberry Pi device, which has CEC support already onboard?
Since when do you need a Pulse-Eight adapter for a Raspberry Pi device, which has CEC support already onboard?
No idea, I just repeat the messages that come when I boot up the RP4. As I wrote above, I switched the HDMI cable into the other slot (the one directly next to the power plug) and I got the two pulse eight messages, the second being "TV".
