Comment 7 for bug 1175579

I found out that if you go to keyboard settings, then redefine the shortcuts for switch to workspace above and below to something then back to Super+up/down, it is working again.
So something happens that confuses unity.
I understand that this is not a very practical work around but maybe if I can script this it would take just a quick command line instruction to fix this...

Something like this maybe:
#!/bin/bash
echo "Reseting shortcuts..."
gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-down "['<Control><Alt>Down']"
gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-up "['<Control><Alt>Up']"
echo "Sleeping 2s..."
sleep 2
gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-down "['<Super>Down']"
gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-up "['<Super>Up']"
echo "done!"

This seems to work for me but I have to test more :)
Let me know if you have a better way!