@samhinchcliffe Thanks for getting in touch. Sorry to hear you are facing this issue. When you access?Search Console?directly, using the same Google account which you’ve used to attempt setup for Site Kit do you see the same URL?
Could you please try and first follow the troubleshooting steps here to see if you encounter the same while in troubleshooting mode with just Site Kit active?
Are you able to set up in Site Kit if you manually add this in Search Console? If you are still having troubles after all of the above could I please ask you to share your?Site Health information?and we can investigate this further. You can?use this form?to share privately if preferred.
Let me know if you have any questions on the above information.