I searched a lot for this and it seems i'm not the only person that have this problem.
Possible solutions:
Update to the latest version of Windows.
Reset your launcher.
or
Contact Microsoft Support.
MC-245888
No matters if you are +18, you cant play multiplayer?
Resolved
Invalid
0
https://minecrafthopper.net/help/guides/xbox-privacy/
Try this first to see if it helps 🙂