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If you're having this issue with 11.5, our engineers are aware of it - please see this topic for consolidation of these problems.

I just started getting this message above and cannot find solution.
That message is displayed and I cannot export "any" music into my USB drive. It will create the folder in USB with Playlist, but will not export any songs to USB whatsoever.
Below are the actions I have already tried. Help is needed.
I use Macbook macOS Big Sur / v 11.5
1. Deleting and re-installing Rekordbox.
2. Formatting USB drive / using other USB drives.
3. Creating another playlist and try exporting the playlist.
3. Going to System Preferences > Security & Privacy > Giving Rekordbox the access to all files and folders (the access was already given)
Is there way to get support for this issue / or someone who can help me?
Thanks.
If you're having this issue with 11.5, our engineers are aware of it - please see this topic for consolidation of these problems.
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I am having the very same issue. Yesterday morning I updated the OS on my MacbookPro to Big Sur 11.5 and updated Rekordbox to Version 6.5.2. Now I cannot export any of the tracks in my RekordBox library to any of my flash drives. Not a single track will export. And I've tested this with multiple flash drives, one of them which has 40+ Rekordbox playlists already on it (so I know the flash drive isn't the problem). Dragging and dropping the playlists from my library onto the flash drive does not work. And the Sync Manager does not work either. Every single time I get the "One or more files were not exported. Check the log file saved in the "Documents" folder." PLEASE HELP!
I'm experiencing the same issue (which I mentioned in the following thread). Probably related to the Mac OS Big Sur 11.5 update. I do hope a new update of Rekordbox is going to be released very soon.