I am onStudio One 3.5.4.45392 OSX x64 (Built on Nov 30 2017) and just purchased a new MCU Pro, and after selecting the Mackie Control protocol am getting this same message and it logs of. Also says " Falscher Sicherheits Code", whatever the heck that is. Only way to reconnect and have it work is to disconnect it in S!3 Pro and then reconnect it. So it appears to not be fixed...
Please help!