OK, I get it now - sorry, bit slow today. I've installed your Test workflow, but it specifically asks the Finder for the selected items, and when you control-click an item. the Finder does not change the selection. (And hasn't done since 10.5.)
Because asking the Finder for "the selection" does not work reliably, FinderPop ends up having to do all sorts of horrible munging under the hood to find out what it really was you control-clicked. This works fine for me and presumably everyone else using FinderPop, so there's something different about your system..? Any ideas - anything unusual about your system? Any odd prefpanes installed?
If anyone reading this has similar problems with FP, could you please chime in and maybe we can find a common denominator here...