Mission Control not working (Mac OS Catalina 10.15)
Try to restart the Mac's Dock, follow this link fix the problem for me:
https://www.defaults-write.com/fix-for-not-working-exposemission-control/

To solve this problem apply the following defaults write command:
defaults write com.apple.dock mcx-expose-disabled -bool FALSE
Restart the OSX Dock:
killall Dock