LightDM results in no HDMI output (blank screen), even though the service appears to be running normally.

[nnovation]

On a Raspberry Pi 5 (8GB), starting LightDM results in no HDMI output (blank screen), even though the service appears to be running normally.

🖥️ System Information

Device: Raspberry Pi 5 (8GB)
OS: Raspberry Pi OS (Debian-based, 64-bit)
Display Manager: LightDM
Window Manager: Openbox
Output: HDMI

🔁 Steps to Reproduce

sudo systemctl start lightdm
sudo systemctl restart lightdm

when start this start lightdm so output blank screen and test my below commanf

start test using command 'startx' but nothing
also try my flutter app using Command = DISPLAY=:0 ./trial

in outputside nothing heppen