Can't use keyboard shortcuts to switch spaces unless I'm in mission control I have my Mac set up to switch spaces using Cmd + Num but sometimes, out of the blue, they will stop working unless I do the command when in mission control. Anybody have any idea why this happens?
I've found that some mission control problems are resolved by restarting the "Dock" process (which handles the job of Mission Control).  If you care to try that, the Terminal command is:

killall Dock

(But first use killall -s Dock to make sure the command will only kill the one process.)