Do nothing on Laptop lid closed

I have a thinkpad hooked to an external monitor and I want to be able to close the laptop lid and still use my monitor as an external display. Unfortunately, this is not a feature supported by xfce, so I’ve manually changed the settings in etc/systemd/logind.conf and uncommented the following lines

HandleLidSwitchExternalPower=ignore
HandleLidSwitchDocked=ignore
LidSwitchIgnoreInhibited=yes

which was suggested in this thread

Finally, I did this step xfce:xfce4-power-manager:faq [Xfce Docs]

However no changes are taking effect? Any ideas?

Have you rebooted? Have you set the external monitor as Primary display?

Yes, I just tried setting the external monitor as the primary display.
It works for around 15 seconds then the external monitor goes black

Not an expert at this by any means. If it is connected by HDMI can you rule out a bad cable by trying another?

The cable is almost brand new. Highly doubt it would be the cable.
Setting the external monitor as a primarily display, made a slight slight difference. Prior to that, the external monitor would immediate go black. So there’s progress in that sense. Anyway, thanks for your help.