What happened: I first set a wrong variable name, then found the error and fixed the variable name, but somehow the game object was never set in the other FSM.
What I found out: during play, it loaded the wrong variable name I had used earlier, and did not use the new one.
Workaround: I could duplicate the state (with the correct variable) and hook that up instead and this worked.
Likely bug: when looking into the code of the action, it does not reset the variableName.