I was using workplace switching for a long time and it suddenly stopped working today. Even after a fresh install, (some config left over as I preserved my /home folder).
Super + S still raises to show all work-spaces.
Clicking on a task-bar icon representing a window in another work-space no longer switches to that workspace + window.
Ctrl + Alt + ⟵ (any direction) no longer works.
Ctrl + Shift - Alt - ⟵ (any direction) no longer works.
I've verified that those key combos are registering by redundantly re-assigning the shortcut mappings.