Are you by chance using an RPi4? If yes, we are waiting for this issue to be resolved KMS: blank screen after TV is brought out of standby on modes that need scrambling · Issue #4486 · raspberrypi/linux · GitHub
Just configure kodi display settings to 1920x1080 and whitelist the 3840x2160 modes, then you won't hit the issue when in kodi GUI.
so long,
Hias