Formula in Parameterized Blueprint Not Allowing Variables

[CrimsonKnight]

I am trying to make a parameterized blueprint in sandbox mode, but it won't allow me to access any variables of parameters higher in the list. All I get is an error, and it doesn't work. It doesn't show in the image, but I get the error no matter which parameter I enter into the formula.

[Loewchen]

Post a screenshot of the actual error or the save file and add the version to the title please, see 3638.