HDMI Doesn't Output Video When Plugging in Display After Boot

ISSUE: Raspberry Pi does not display video output when connecting HDMI monitor after startup. Keyboard and mouse input do not wake up display and rebooting outputs video. Raspberry Pi is responsive to ping/ssh and other services.

RESOLUTION: This functionality is disabled by default. To enable, edit /boot/config.txt and add/uncomment the line hdmi_force_hotplug=1. This file also contains disable_overscan=1 which will fix issues with black borders if not set up during initial configuration. Once changes to the file are made, a reboot is needed to apply.

As the file requires root permissions, can be edited with sudo nano /boot/config.txt.