Sometimes whilst I'm playing the game (in full screen), the components on the launcher will disappear. When I hover my mouse in certain locations (where the buttons should be), the component I hovered over reappears.
I have no idea what's causing this.
Please retry with the new "Installer / Launcher" from https://minecraft.net/download and see if that happens too in that version.
But, this is most probably not a Launcher issue, this is more an Operating System issue, happens in other programs too when the system is overloaded.