I have migrated my Mojang account some time ago but never had the luxury of time to play. Finally, when I found the chance, I logged in using my Microsoft credentials and everything seemed ok. That was when I saw that my "Play Minecraft" button was replaced with a "Play Demo" button. I tried to find out from "Minecraft Help" what was going on, but to no avail. I am making this ticket today to ask you if there is a way to fix this.