Hi @rainerle
Did you try restarting your machine having the device unplugged?
Restart is better than Shutdown. The Restart cleans up UEFI-system-driver cache which could contain invalid device info.
Did you try with and without the driver-filter? This can be found in the WaveForms DMG
Old macOS version require the driver to be installed, new macOS versions don't require it, on some new Mac hardware it may not work with the driver.