External display shuts off when I close macbook pro lid

I have tried everything I can think of. I have done multiple restarts and NVRAM restarts. I am using a usb mouse and keyboard, my macbook is connected to power, and I'm using a USB-C to HDMI cord. Once I shut the lid, I get no signal from my external display, and moving/clicking the mouse and mashing the keys does nothing. I have noticed that it is still registering my clicks and key presses on my mac, because sometimes when I open the lid back up some files and folders are open.