Imported Aperture library into Photos, "Show Referenced File in Finder" does nothing
I had a similar issue, which seemed like it had something to do with access permissions. Try the following:


Pick a random photo for which "Show Referenced File in Finder" does nothing.
Select it and hit space to view it.
Photos will pop up a dialog saying that it can't access some files outside the Photos library and will ask you to select a certain folder (for me it was the root of all my referenced files).


After I'd done that, "Show Referenced File in Finder" now works for all my images.