RTK messages in MAVLINK

Hi there - first time forum user, so apologies if in wrong section.

I’m trying to setup an Emlid Reach RTK system with my Pixhawk (Not Pixhawk 2). I have a GCS running Mission Planner 1.3.46, Emlid Reach connected via Ethernet over USB (I can see the data being received by Mission Planner on the RTK/GPS inject screen), and a 433 MHz radio attached to the GCS via USB.

On the UAV, I have a Pixhawk running Arduplane V3.7.1, 433 MHz receiver plugged into TELEM1, UBLOX M8N plugged into GPS, and the Emlid Reach plugged into SERIAL4/5. I’ve changed the configuration on the Pixhawk on Mission Planner according to Emlid documentation (https://docs.emlid.com/reach/ardupilot-integration/, “Configuring ArduPilot to accept Reach solution”), and changed parameters to allow arming with only GPS modules attached.

When looking at the status tab in Mission Planner, GPS1 (M8N) shows a GPS status of 4 (DGPS/SBAS fix), but the Reach RTK module only ever shows GPS status of 3. In addition, when I connect to the Reach modules via Wifi, the builtin Reachview App shows the rover operating in single mode, not RTK. However, when I connect the two Reach modules via Wifi, the rover enters RTK mode, which makes me think that the corrections are not being transmitted via Mavlink/being transmitted from the Pixhawk to the Reach for RTK correction.

I have been downloading the datalogs to examine the Mavlink messeges - what should I be looking for to check if the RTK corrections are being transmitted- is it messages tagged “mavlink_gps_rtcm_data_t”? In addition, is there a way to examine the data being sent along Serial 4 to see if it is being transmitted correctly?