Hi Jakutash
Thank you for the details. If the GS-911 does not detect a fault code, that means that this light is associated with a mechanical problem that does not throw out a fault code. Just went through a few forum posts online about this particular warning light, and the general consensus is that it's a flakey/faulty wheel sensor. One of the write ups on this was on ADVrider about a R1200GSA (oil cooled) with the same issue:
https://www.advrider.com/f/threads/brake-failure-warning-light-and-the-yellow-triangle.1147375/As a quick sanity check, there are micro switches for both the front and rear brake lever/pedal that could in theory cause this, you can check this by running Real-Time Values in the GS-911 software. Select the front and rear brake switch and actuate one at a time to see whether the actuation is detected. If it is, it's most likely going to be the sensor.
Kind regards
Ruan