I was using OGNL that called a action to pull in a list of pre-defined answers based upon Configuration Elements.
Old...
GetAction("com.path.to.action.folder","action").call( #variabeToPassToAction)
My variable to pass to action was a Configuration element category that I had stored as a variable in the workflow.
New...
Input Form Select the field
Select Values
Value Source Select External Source.
Search for the name of your action. (my action was imported from a 7.x environment. Before I could find the action I increased the version of the action.) You don't want path.to.action/Action. Just the name of the action
Then the input fields should appear below.
Good luck
Adam Flaig