Hi
When I create a midi track with VEP7 in Mixbuss 6.1.22 , I must only use VST instead of AU because the VEP7 AU is bypassed by default and don't open !! This is the same with synchron player !! The Vienna Instruments is ok with audio units in Mixbuss 6. The others plug ins instruments are ok, it's only Vienna VEP7 and Synchron.
I'm on Mac OSX 10.15.7, Mac Mini 2016 with 16 Gb of Ram in network with Mac pro 8 Cores 2008
Thank you to take a look at this issue.