Unable to Add a New Account

Hi, maybe it'ss an error from your console, you can erase the cache (press and hold the power button from 10 seconds and then restart again)

SO i had this issues liked to kill my son over it. I ended up removing all the gamertags and still couldn't add one. If I remember correctly I ended up doing a factory reset on my console and adding the gamertags back,

Have you tried doing a power cycle then adding the profile?

https://support.xbox.com/en-US/xbox-one/console/power-cycle-console

You're most welcome Tommy! Thank you for allowing me to assist you.

Regards,
Kyle

Hi Tommy. My name is Kyle and I'm an independent advisor.

I understand how frustrating it must be that you are unable to add a new account to your console. Try power cycling your Xbox:

Turn off your console by holding the Xbox button on the front of the console for approximately 10 seconds. The console will turn off. Turn your console back on by pressing the Xbox button on the console or on your controller.

If that doesn't work, please ensure the latest updates are installed by going to Settings > System > Updates. If you see 'Console update available.', select it to begin the update. If you see 'No console update available.', your console is already up to date.

Let me know if these steps help, and if there's any other steps you've already tried, please tell me what steps they are.

Thanks,
Kyle