From my PC Edge Browser, Samsung Find My Mobile website returns a "Network status: Offline" for my Galaxie S8. It was working fine a few months ago. It fails the same way signing in to the account from the S8's Settings-> Password and Security-> Devices-> Find My Mobile" option. I am able to sign in with no problem and get the 2-factor authentication code from the messenger app on the "offline" S8. Can't find any settings changes--all are correct. The only thing I've come across is that Location Services is only showing Google location services--no Samsung.
Give this a try: go to settings > Biometrics and security > Find My Mobile, do you have remote controls, Google Location services , and remote unlock turned on?
Does you have the GPS location turned on in the settings of your device?
Thank you for that information. Can you please send me a picture of the screen when you are trying to track you device in Samsung's Find My Mobile in a private message: http://bit.ly/2JH2rq2