I am experiencing the very same issue. I've tried everything suggested in the forums and absolutely nothing will fix it. As everyone else has said, the tracks load into Rekordbox fine and will play without any issues, however they won't export onto my USB and this same error message comes up.
Please help? This is extremely inconvenient and I also have gigs this weekend so this is URGENT.
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I had this issue three days ago and performed this workaround which I can't seem to find the thread. Assuming you're running the latest version of MacOS of course:
https://www.youtube.com/watch?v=2YQz4c7_Zf0
From a terminal window on MacOS Big Sur 11.5.1 or 11.5.2
run:
sudo xattr -cr <path to music files>