Glad you figured it out! Good call on the junctions switch - I thought it might be something like that. Watch out for cross-volume links, though, as Shadowspawn doesn't do cross volume. Not sure junctions *can* cross volumes, but just in case.
This is for anyone else reading this and has encountered this problem. I ended up using /XJ on robocopy to exclude junctions and /R:1 for 1 retry instead of the default of 1,000,000 and /W: 2 for delay between retries to 2 seconds instead of the default 30 seconds. Yes, that is right, the default retry settings would take 347 days to finally give up on a file.
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