Hi.
Found it, its one of the official actions.
On line 21 uihint is set to FsmBool
[RequiredField]
[UIHint(UIHint.FsmBool)]
public FsmString variableName;
Should be :
[RequiredField]
[UIHint(UIHint.FsmEnum)]
public FsmString variableName;
You can change it if you wish, it will be resolved on a next update