In earlier versions of the Engine (reported from 4.2), in a Blueprint Function Library, from the New Function Node you could right click on "new parameter" to promote to variable. Also you could drag off of "new parameter" and access previously created variables. (*See attached pictures.)
In an update the user explains that now, "if you create a function, then use the data variable it impossible to relate only to the originally created functions. "
Open Third Person Project in UE 4.5.1
Create a new Blueprint>Blueprint Function Library
Open to "Graph" tab
1. From the New Function Node, right click, "promote to variable" is grayed out.
2. From the New Function Node, drag from "New Param" to access the drop down menu; "Promote to Variable" is no longer an option
Head over to the existingAnswerHub thread and let us know what's up.