I am having the same issue with rpi 3 and kodi 19. When I turn off the TV and come back to it the next day, I can't get kodi to wake up using any keys on any remotes. I have to turn it off and then on again.
When the TV is switching off, the RPi stops A/V output by default. When switching on the TV, there must be miscommunication between your RPi and TV, so A/V will not switch on.
Go into input device settings, and select CEC adapter. Change the CEC settings to ignore TV switch-off signal. So RPi's A/V stays active all the time, and should still run when you switch the TV on again.