Windows logo key+number don't work with more than one open programs

I work with several windows, several programs at the same time. Sometimes more than 20 at once. My workflow becomes to heavily use Windows logo key+number to jump from one to another.

Example: I have Outlook and a mail open. If I tick two times Windows logo key+number -> it gets me directly to that mail. Recently this tactic doesn't work anymore. I just see a bar, if I hover the mouse I see all windows.

I use 7+ Taskbar Tweaker on all of my machines, but just one makes trouble. I uninstalled it already.

Don't know what to do, just went me crazy already.

Anyone out there an idea? I am using overall WIN10.

Thank you.