Experiment. Load 2 instances of Mobius and see if they will sync together directly, ignoring the host time (Bidule can do that, for VST at least ). This might give a better idea of where the problem is.
i.e. In order to problem solve sometimes it's informative just to do an experiment. It doesn't solve the problem directly, but often throws up useful information that helps solve the problem. You're currently in a bad position, in that the info you provide doesn't tell enough to know the source of the problem. ...and even Per hasn't come across it before. Whether it's Bidule, or Mobius, or something to do with the mac OS and drivers. I'd guess it's either a Bidule or a Mobius thing, both have forums and guys to help. ...but where to ask first? If all the Mobius functions (including sync) work when it's hooked up in a different way then you'd start at the Bidule forum. So it may seem that people trying to help are suggesting random stuff that doesn't help, but really it's the need for more info. sorry to not be a big help, and yes in many ways old XP was nicer, it actually displayed error messages rather than just shutting down your program without explanation. good luck andy