You could try key id 230 as some TV’s will send that out instead. I believe with CEC you must use a key id as they don’t map to names the same as other remotes do. Unfortunately CEC shows bogus names in the logs for handlekey events and those names do not work if you try to keymap with them. If that doesn’t work then just uninstall keymap editor and then install it again from Kodi’s repository. It did get updated for Kodi v19. That add-on is by far the easiest way to discover the id’s.