Hi @MrBramme,
I’ve come across this thread while searching for a similar pattern to what is happening to me and bam! your post describes my very same scenario. My iPhone 6s Plus is perfectly tracked by HA whereas my wife’s iPhone 6s isn’t. Both of us are running 11.4. Whatever I do, HA tracks me well, but doesn’t track her at all, and it had worked well for both of us in the past. Have you had any success addressing this specific case?
Thanks