No signal when plugging in HDMI after booting

I have an Inspiron 7586 with an Intel Core i7-8565U and integrated UHD620 (Whiskey Lake) graphics.

If I boot macOS before plugging an external display into the HDMI port, when I plug in the display, all I get is a no signal message. Strangely enough, macOS detects the display and acts as if it's connected - it shows up in system settings, and I can move windows and the mouse onto it.

force-online is enabled in the device properties. Without it, I need to turn my screen off and on again after booting for macOS to detect it.

Additionally, my connectors are mapped correctly.

Does anyone know what could be causing this?

My OpenCore config.plist is available on GitHub.