Here3+ GPS cannot be seen on CAN when FDcan is enabled?

While troubleshooting running multiple Here 3+ GPS units on one CAN line, we discovered that the FDcan solves unhealthy GPS messages. However, once FDcan was enabled on both GPS, the GPS units no longer appeared on the CAN page in Missionplanner, either through Mavcan or SLCdirect.
The GPS units work and continue to let the drone operate with no GPS errors, but we are unable to see/edit the GPS units over the can network, which means we cannot turn off the FDcan or change any node ID’s.

Is this a bug with FDcan and the software? Or is there a solution for this?

Mission planner 1.3.80, build 8479
Arducopter 4.3.3

Related GPS thread can be found here:

Further info to help document the issue:
The CAN_D1_UC_OPTION parameter appears to make no difference, whether CanfFD is set to on or off.
The GPS units appear as garbled messages using SLCAN direct (image shown below of parameters)
No solution has been found to interface with the GPS units once FDCan is turned on

@CjF Please try DroneCAN GUI Tool to connect instead and see if that’s able to talk to it.Overview - DroneCAN

The image included above was taken from the DroneCAN gui tool, that is what it looks like when it connects.

After working with Michael Oborne, I updated to a new beta version of Mission planner, and there was a small change that allowed me to connect to the FD enabled GPS units. I was then able to change the Here3+ GPS back to normal CAN.

@CjF It will be better if you can provide the steps which you did so that I can follow the same