alasta:1024kb: Turning the account off @ Spark was the wrong thing to do, I'm sorry to tell you.
Apple's FMI system is pretty comprehensive, but it does need a connection to the phone so that you can sign in to iCloud on another device & ask it "where are you?" & the iPhone is then able to respond "I'm here". You then have the choice of various options including wipe & play alarm @ full volume.Correct me if I'm wrong, but I think logging into iCloud via a web browser requires 2FA? If so, then you'd need to have access to another device that happens to be logged into the same iCloud as the lost device?
In my case my iPhone and Macbook Pro are the only devices that I have logged into my iCloud account, so I am conscious that I need to have access to one of them if I lose the other.
I log in without 2 factor authentication, the iPhone is the only Apple device I have.