Corsair.com

You should try this by changing your filter to OISD only and clear DNS cache, a reboot should do the trick and I'd think that would fix the issue but as I don't have a buy directly from their site option on Corsair I can't add anything to test.

Open a second browser window for your policy log page, and click the filters icon, to expand the filtering options of the logs view. Turn on "show blocked only". Next click the icon of the two arrows in a circle, to enable live log streaming. With that running, now go to your other browser tab and attempt to use the website. Watch the log view to see which if any hostnames appear blocked as you try to use the website. Among those will likely be a hostname you need to put into your allow list.

Be sure to disable any other browser adblocking plugins for the duration of your troubleshooting, so as to complicate the troubleshooting process. You can enable them once more after you've taken care of the NextDNS configuration changes. This way you're only dealing with one variable at a time.