This has happened just today. I had changed my birthday on the x-box app connected with my Mcpe account since I realised I put in the wrong number for the date, and my Minecraft & x-box app did not work correctly after that. The x-box app would somewhat work, however I could not see any of my friends profiles, and it was quite laggy. I managed to fix the problem on the x-box app by simply logging out and back in. However, for the Minecraft app, it just shows the loading screen, than goes back to the menu screen. (Idk what you call it?) Basically, the Mcpe app won’t let me in, as it just closes while during the loading phase. Please help.