Possible bug with LED 6 on Ubiquiti bullet XM

I am using the following image:

- aredn-3.20.3.1-ath79-ubnt_bullet-m-factory.bin

on an Ubiquiti bullet M2 XM device.

It works fine.

However the top LED (LED 6) does not light.  It is working and flashes while booting, but it does not light during operation.

The device works just fine.

My suspicion is  that there is a bug in the code which thinks there are either 7 or 8 LEDs and it is trying to light a non-existent LED.

thoughts on help for debugging?

Thanks!