Trimble R12i RTK Inject to Mission Planner

Attempting to Connect a Trimble R12i to Mission Planner via RTK Inject. Configured the Trimble to Output via USB RTCM3 at 115200 baud rate. The Trimble is connected to the computer via USB however upon selecting the Com port, Baud rate, and then clicking connect. After this, I still get 0 for Output data rate, input data rate, and total messages seen.

The end goal is to run an RTK setup utilizing a Trimble R12i as a base station connected to the computer with an Emlid M2 as the aircraft unit. No such luck so far, any assistance would be greatly appreciated.