No output in Pronterface SKR e3 mini v3

[Dapperdreadful]

When I am doing commands in Pronterface, I am not getting any output. It is connected via USB and responds to commands, but just doesn't return any output.

For instance, M303 E0 S240 will start PID tuning at 240 degrees. However the terminal in Pronterface remains empty except for the command text.
M500 will produce a "Settings stored" message on the printer LCD.
If I send M503, I get nothing back.

SKR E3 Mini V3 on Ender 3 Max connected to Windows 10 computer via USB

I am currently connected at 115200 baud rate, no other terminal connections are active. 

My marlin firmware:

#define SERIAL_PORT 2

#define BAUDRATE 115200

//#define BAUD_RATE_GCODE     // Enable G-code M575 to set the baud rate

#define SERIAL_PORT_2 -1

#define BAUDRATE_2 115200   // Enable to override BAUDRATE

I also set the Bits per second to 115200 in device manager.

Windows Device Manager shows:
Ports (COM & LPT)
>>USB Serial Device (COM3)

Not sure if this is using the correct driver tbh, I installed I installed maple_serial usb driver with driver signature enforcement turned off, but when I tried to update driver I browsed to Marlin\src\HAL\STM32F1\maple_win_usb_driver and got the "The best drivers for your device are already installed" message. I also went into that same folder and right click> install, which gave me the unsigned driver notification, and I installed anyway.

Thank you in advance for any help you can provide. I am happy to include more information/screenshots.