31 July 19 - We are still working behind the scenes to try and pinpoint the issue many of our players are having with signing in, and hope to have it resolved soon. Thanks to everyone who has provided valuable information in the comments, which helps us greatly when trying to reproduce the bug. Thank you for your patience!
After installing the game for the first time and going through he process of linking the Switch to my Microsoft Account. Minecraft signs in fine and cross play can be done.
When I exit the game and start the game up it will not sign into my Microsoft account.
I have tried turning the console off which didn't work. I deleted the software and re-installed and it still didn't connect. I then deleted the software and save data, re-installed from fresh, set up the link from Switch to Microsoft account and all works fine until I exit the game and the process repeats again.
Any help or ideas would be appreciated
Several people have been able to work around this problem by logging in to Xbox Live using an email account instead of a phone number. Mojang is aware of this and will be working with the Xbox team to resolve it. However, there may be multiple causes of this issue, so if you've tried logging in with an email account and still can't connect, please comment below, mentioning whether it's an account you created via the link from the game or a previously existing Microsoft account. (Please omit personal details.)
A sudden influx of new comments has been occurring on this report. Many of them say that the connection actually succeeds, but they get an error message anyway. Xbox marketplace has very recently been making changes that might be related to this error, which might or might not be related to the original issues on this ticket. We are looking into it. In the mean time, you might also want to monitor the Xbox Support Twitter feed, and perhaps even mention your experiences there.