Rekordbox Track export

Hello!! 
I am using Rekordbox 4.5.0 on my MacBook Pro 10.11.6 OSX EL Capitan. 
I tried to export one big Folder containing 4 Folders with Tracks onto my USB stick- going the classic way via the SyncManager. I do all the steps and you can see it exporting in the small bar at the bottom.
But then there is nothing on my usb Stick.
When I do it again, it’s says the Folder Name XXX is on the Stick already,wether I want to replace it or not.But there clearly isnt. 
The USB stick work completely fine, checked that several times.
What to do ?? 
Thank you guys in advance !!