Omnibus F4 SD - Telemetry via serial modem fails to load parameters

I have two Omnibus F4 SD boards (the AKK version) and they both are unable to send parameters to my GCS. In QGC I get a warning saying “unable to retrieve full parameter set from vehicle” and in Mission Planner the parameter download progress bar just doesn’t move. The live data such as GPS position, attitude, altitude, etc works fine. I’ve tried two radios, Dragon Link telemetry and RFD900X. Both have the same result. I’m using 3.9.8 plane. Has anyone seen this issue before? Or does anyone know what serial port corresponds to the one in the attached picture?

I was having this problem with an Omnibus F4 Nano V6.1 board and setting SERIAL1_OPTIONS to 4 (half duplex) seems to fix it