Minecraft account disappeared after forced move from Mojang to Microsoft

Thank you! This wasn't obvious to me AT ALL. They really should add this to the steps for migrating your account.

Hi there Boaster welcome to the community forum! Christopher here, an Xbox fan just like you and has been on Xbox for years already. I would really love to make your day by helping you out. You can try this advice!

For those of you having this same problem, there is an important step that Microsoft and Mojang leave off all of the FAQs when they just repeat to sign in with your Microsoft account. From the Launcher log-in page, you have hit the button to go back to the accounts page. But then, don't click on your existing account that you want to sign into or you will just get back into the same problem loop that won't let you sign in. You have to add a new account. It is counter intuitive, because you are not actually setting up a new account. But once you click to add a new account you can choose to sign in with your Microsoft account in the Launcher. Once you do that, it will automatically use the Microsoft account to log you in from the Launcher. And my worlds were there without change.

Yes, it is possible to install Minecraft Bedrock Edition on PC, in the Launcher it appears with the name "Minecraft for Windows".

Regarding the migration question, don't worry, your Minecraft Java Edition will not disappear, the only thing that will change is that the game license will be linked to the Microsoft account where you migrate it and after that to be able to run the game you will only have to log in with your Microsoft account instead of your Mojang account.

It's a new Microsoft account and link it to your existing one

Hello, My name is Jesse. I'm an Independent Advisor and a member of the Microsoft community and I'd love to assist you today.

It's not in the migration instructions, but after the migration, you have to ADD a NEW account, and link it to your Microsoft account. Startup will take longer, but it sure works.