Issue with URL being blocked as phishing. Whitelisting URL doesn't work.

A staging website (to display the business website first and do changes before applying it to the actual website) created by administration for has been blocked as "phishing" and despite several attempts we are unable to whitelist the url, with nothing changing.

It reads: "Access to the site you have requested has been blocked by your policy."

I cannot find where the conflicting error is within the policy, firewall or web filter. I'm not too familiar with group setting changes, so maybe that could be it.

I've contacted Fortigate and they've even managed to change the flag for the specific site we've created to Information Technology instead of Phishing but the website is still blocked for Phishing (both externally and on our intranet).

Does anyone have any idea how to fix this or what we could try to fix it with?