there have been a ton of start men issues with win 10 and i have yet to see any solid solutions to this and other similar problems. the only thing i have seen repeated over and over is to log off and back on and hope that helps.
that or create a new user and that one's start menu should work the way it should. not the best solution i know but that's all i have seen. never actually had any start menu issues myself so not had to play around any myself. i tend to use classic shell anyway as i like the older look. this also fixes the issues since it replaces the new menu with an older style.