This only started happening recently after using DisplayFusion for years. When I click the start button on my 2nd monitor it opens for a second and then closes. I can't get it to stay open. On the main monitor it's working normally. Talking about the classic Windows 7 style menu not the Windows 10 one.

EDIT: Nvm. Fixed by installing latest beta version of DisplayFusion.

@Ashey Thanks for the info anyway. I had the same problem and can confirm it is fixed with the latest beta version.