I got the same problem
as I said my r 1200 gs adv has the same problem, as soon as I took it to the dealer they said that the pressure modulator was broken, It casually started failing a soon as I picked it after the 40000 km service, my dealer recommendation was to change the modulator which cost around 2000 dollars, i have not done it yet. Do you think that i should change it, or look if something else is not working properly? and its this a common issue in this motorcycles because it seems weird to me that it stopped working right after i took it out of my dealers workshop?
PS: sorry for bad English its not my mother language