Website flagged as malicious by Fortiguard and yet on another device Fortiguard shows no problems

I was using a different laptop with Fortiguard safety on and my website was blocked. It never happened before, so I did couple of checks on safety sites such as VirusTotal and all of them show no problems, no malicious elements, what is weirder - including Fortiguard part. How can a website be marked as safe and not safe at the same time?