MacOS – ‘Show Desktop’ Mission Control/Expose Not Functioning

If you exposé (three finger swipe down or whatever shortcut you've set up) you can then switch through all of the applications by pressing tab.

Pressing tab on its own will go through each application showing all windows (minimised or not), pressing cmd and tab will show you the swap icon bar (in middle of screen) at the same time as going through the applications. The arrow keys followed by enter will help you select what window you want.

It's certainly not as elegant as SL used to be, but it's the only thing I've found that kinda/sorta/maybe comes close.

Did you try double-clicking on the actual keyboard short cut for that function in System Preferences/Keyboard/Keyboard Shortcuts? You can change the key combo at will. Of course there is no guarantee they will take, just as your "Restore Defaults" did not take.

I use Spark, a free app that lets me map anything I want, and overrides the OS settings. If there is a con flit (which shows as the yellow triangle/traffic cone), I change the OS conflict to some unused combo.

I complained to Apple that I could not change those keyboard shortcuts to "Open app X". The response was that I should not try to do that, as the existing system was working as designed.

This is not a built-in cure using the native OS options, but it works.