I've had this issue of being unable to connect to my Microsoft Account from my Nintendo Switch for over 6 months. I’m not going to delete my data because I’ve put many hours on my worlds for a method that many people say that it’s just a momentary fix.
Now, hopefully this information is useful:
I am using an existing account that I made to play Minecraft on my phone, I am able to sign in into it
I use an email address to log in, but I do it on my phone
When I click on the “Sign into Microsoft Account” button, it gives me a link and a code. I’ve done the process over 10 times, and on my phone, it says that I successfully logged in, but on my Switch nothing happens, I don’t even get an error code, and I don’t log into my account. When I click the “Sign into Microsoft Account” button again, it asks me to do the same process all over again, but as many times as I try, nothing happens.
I just wanted to update
I had this issue for more than 6 months, but after the last update it got fixed! (I even bought a realm) I posted a previous comment giving information on this same thread and for me it got solved. Thank you for working on it! I hope it can fully get fixed for everyone soon.