Official comment
1. Disconnect your DJM from the computer.
2. Close rekordbox dj.
3. Uninstall the DJM driver from Control Panel > Programs and Features.
4. Reboot Windows.
5. Install the driver in administrative mode (right-click the driver install file > Run as Administrator)
6. Reboot Windows after the installation is complete.
7. Connect the DJM to the computer.
8. Launch rekordbox.