I have created a custom board based off of the Arduino Lillypad USB board. I also wrote a simple library that wraps the Keyboard library and provides some other functions to work with my board. The library and board files can be found here: Scanner-Pro-MK3/arduino_board at master · oschwartz10612/Scanner-Pro-MK3 · GitHub
My problems comes when trying to compile the simple sketch. On macOS it compiles fine and uploads, but on Windows I get the following error when compiling with my board.
fatal error: HID.h: No such file or directory #include "HID.h"
It is my understanding that Keyboard only compiles correctly if it is using a supported board. Lillypad USB should be compatible and is the derivative of my board, though some things may have changed and I am unable to identify what those are.