Restore the keyboard shortcuts from a backup copy, or rebuild them.
Thank you for your input.
I have no backup (Yes... I know) and rebuilding did not do the trick.
So now i worked around the problem wit assigning my workspaces to the 6th workspace and upwards.
Not the best solution, but a good workaround. It works at least.
Are you saying that you could not add the shortcut to the set?
Yes. I can´t find any way of adding the missing shortcut to the set.
User defined workspace 1-5 is just gone. Somehow.
Still I can live fine with my workaround. That is until more start disapearing, I HOPE NOT!