Arduino UNO + Dynamixel Shield: software serial gives garbage output in serial monitor

I have connected a single XL330-M288-T servo to a Dynamixel Shield, which is mounted onto an Arduino UNO. I downloaded the “DynamixelShield” library and I am trying to run the “DynamixelShield/basic/position_mode” example script to make sure everything is working okay.

In this example, two serial connections are setup: one is software serial on pins 7 and 8 to send back monitoring info to the serial monitor on the Arduino IDE, and another is hardware serial on pins 0 and 1 to send instructions to the Dynamixel servo.

The problem is, the info sent back via software serial prints garbage onto the serial monitor (see image below).

However, the movement instructions ARE being sent to the servo, as it is clearly moving as expected. So hardware serial seems fine. Any thoughts on what could be the issue causing this garbage feedback on software serial?

The Arduino UNO and Mega require the use of the UART port on the DYNAMIXEL Shield for serial monitor output, rather than the USB connection.