Mxtoolbox.com Not Blocked But Does Not Load

I'm a new user to NDNS and I noticed that mxtoolbox.com doesn't load. There is no 404, just a blank screen. I looked into the logs and only 1 tracker domain was observed blocked, so I added it to the allow list. However, this did not solve my issue. If I change my DNS to 1.1.1.2, then I'm able to view the site.

I troubleshoot it further by loading the browser developer console, while still using NDNS, and see that a javascript was not loaded. I added cloudflare.com into the allow list but still does not help the situation. From my Windows PC, while on NDNS, I can't ping cdnjs.cloudflare.com. As soon as I switch to 1.1.1.2, I can ping the domain.

I think my issue is something related to the security features of NDNS but I'm unsure. From the logs, I'm not seeing anything *.cloudflare.com being blocked