BigSur Runs with Graphics Acceleration on ASUS xf512fl but HDMI not working, help!

So, I installed bigsur using an efi which I created on my laptop. Everything works except the HDMI, which outputs nothing. The laptop display goes black and then comes on again, the monitor is unaffected. What could possibly cause this? It has an Nvidia GPU which I disabled. Please advice if you can 😁