I've seen several other threads about blank screen issues, but seems that my case is little different.
This one is similar to mine, except the fact that my board does not support CEC and I cannot fully relate it to switching on/off the TV.
In My case it happen occasionally, when I come home from work, I switch my TV to the LibreELEC's input (the box is running 24/7), I see the blank screen. At the same time I can access it over the network (Ping, Samba, Web, SSH), and can play the movies. When I start a movie using a Web interface, the TV switches the refresh modes as normally, there is sound, but no picture. Addons (transmission, rtorrent) are working fine. Seems that all is working except the screen, which is black. I cannot reproduce the issue intentionally.
Kodi restart does not help,
# systemctl restart kodi
only reboot brings back the screen.
I'm not an expert in linux and don't know where to look. I attached log files. Not sure which one is needed, so attached several. Hope this will help to find the reason.