Hello. This will hot be a solution, as I haven't figured it out myself... I have tried to get my own Leonardo board working and it too stalls out on receiving the GUI
But more informative I hope.
The Leonardo is a bit unique with it's USB connectivity... the following is excerpts from the Arduino site
The Leonardo differs from all preceding boards in that the ATmega32u4 has built-in USB communication, eliminating the need for a secondary processor
Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data using the ATmega32U4 hardware serial capability. Note that on the Leonardo, the Serial class refers to USB (CDC) communication; for TTL serial on pins 0 and 1, use the Serial1 class.
So basically I think the issue is that the RemoteXY library is trying to communicate over Serial, when with the Leonardo think it needs to be Serial1... but who knows, I could be completely wrong as well
I have also noticed that the library keeps trying to use SoftwareSerial?? There is a HardwareSerial option in the library, but I haven't quite figured out how to get it to compile (let alone use Serial1)
"And voila, which is French for.......'and then I found out.'" - Ready Player One