That is what I thought. The first time I used cmd Z it did nothing. So I started looking around to see why. Then I found the hotkey solution, which does nothing.
Might be cause I have a european/Dutch layout. Or a non mac keyboard.
Found the solution, for my situation.
It seems the keyboard/Spine wants me to use the right cmd key on my keyboard instead of the one on the left. I never used the right one, so didn't think it might be a different key. Just thought it was the same one but for left handed people. Guess not.