I flagged onUpdate doesn't get called on device as "not a real question," since the OP answered it himself as "I don't know what has happened but it started working". I believe it does not bring anything to SO to have such questions that ask nothing and teach nothing.
It was declined. I do mind the flag weight hit, but it is a minor issue to me compared to the fact that I will take other hits if I mark other such questions, which I will do unless I get an explanation I understand to that "decline".
I do understand that human error happens, and maybe I happen to be right with my perception and the person who declined wrong. However, I assume by default I am missing a good reason here for lack of experience, and hence I ask "what was not right in my reasoning"?