Hi Greg Dey,
I'm not sure I'm following what you are trying to do.
User Actions require either an ActorID (user) or a TaskID for assignees. You can either select a "static" Task or User from the drop-down list, or you can select a variable that contains an ActorID or TaskID
I'd recommend checking that the Actor is set up as a Pflow User, and that the Pflow User is associated with the Task you are using. The attached sample flow (you'll have to change the extension to .lpd) uses both an Actor Approver variable and a Task Approver variable, and doesn't have any static approver, and I didn't get any errors. Good Luck Kelly