Sophos UTM 9 - Block Specified URL on Network, Whitelist MAC Addresses

Hello all,

I have a Sophos SG 330 with UTM 9 and am trying to block access to a url ex. https://www.domain.com/page while not blocking the any other page on said domain. 

That being said I also need to whitelist a few devices by MAC address or local IP to be able to access the URL without issue.

So far I have tried going to Filtering Options > Websites > New Site, added the URL, and tagged it with a 'blocked' tag. Then I went to Web Filter Profiles > Filter Actions > New Filter Action > Websites > Control sites tagged in the Website List, added the blocked tag, and changed the option to block. 

Going into the Policy Helpdesk and testing the URL on one of the IPs where it shouldn't be accessible results in the following:

Do I need to remove that URL from the default Business category to prevent my Block action from being overwritten? 

Would really appreciate any help I could get regarding this issue.