I would like to add that we got the same error and its the first time I’ve seen it, and this was on a brand new build.
Let it sit for some time and it didn’t go away.
Rebooted the system (power down) a couple of times and let it sit, still the same error.
In the end I picked it up, moved it about and did 360 rotation, put it down a meter from where it was and the error disappeared.
This is a large copter with a 6 layer centre stack and the external is mounted on a standoff on the top of the stack, 20cm from the PDB and 13cm from the closest battery.
In all the this time working with AC this is the first time I have encountered this error.