Pixhawk 2.1 Full Parameter List Empty in Mission Planner

Hey Ardupilot community!

=Hardware: Pixhawk 2.1 Standard Set
Software: Using QGroundControl for initial setup and data display, then Ardupilot for Full Parameter List configuration.
Issue: Pixhawk connects to QGroundControl just fine, messages with data are rolling in, but when I switch over to Ardupilot, the Full Parameter List is mysteriously empty.

So far, I’ve tried a few things to sort this out:

  1. Successful QGroundControl Connection: Pixhawk is detected, and I can see messages with data.
  2. Ardupilot Connection: Pixhawk is detected, but the Full Parameter List is empty.
  3. Attempted Fix: Changed the layout from “Basic” to “Advanced” in the Planner tab, but it still did not solve the problem with the parameter list.
  4. Firmware Update: Tried updating Pixhawk firmware via QGroundControl, but no change in the parameter list as well.

I’d love to hear your thoughts and advice on this:
→ Has anyone else run into this Pixhawk 2.1 and Ardupilot parameter list mystery?
→ Any tips or tricks you can share about Pixhawk setup that might be eluding me?
→ Thoughts on why QGroundControl is showing data, but Ardupilot isn’t picking up on the parameters?

I am attaching also some helpful (maybe) screenshots. There is also error after clicking restart the parameter option.
I’d appreciate any thoughts or experiences you can share.
Thanks for any help!