Since I installed Norton on my Nexus 6p and enabled the anti theft protection, I've gotten this somewhat randomly. Of course the sim card hadn't been changed, and luckily I do remember my PIN number so it's more of a minor hassle than a big problem..
But I'm curious as to why this is happening? How is Norton detecting my sim card as being changed, when it hasn't been? And I've only had the phone for about a week. I'm also using Google's Project Fi network which changes between T-mobile and Sprint depending on the network strength, so I thought that could be what's causing it..
But I've gotten this message when I'm at home as well and using WiFi, and Google Fi allows automatic WiFi calling so as long as I'm on WiFi the phone shouldn't have to be switching between Sprint and T-Mobile's networks..
It seems this would be a very useful feature to prevent theft, and I would definitely like to keep it enabled. I hope someone can give me a tip on how to solve this little problem.