Nebula3 is not compatible with OSX. You are using Nebula3 Pro or Nebula3 Server. Ensure you are using lasted build available in download section plus check Nebula and MWD are correctly authorized in the local computer.
Sorry, yes it is nebula 3 - not sure how to authorise Modern White Dynamics - I just installed it and there was no Authorisation. All the standard compressor presets work - it just seems to be the sidechain ones that crash ableton live. No problems with any other presets - my version is 1.3.839.
Thought it may be the way ableton handles the sidechain?
mmm I think you found a temporary solution, but the bug is there. I'll publish 1.3.868 RC for windows this night. I hope to put it online asap. I don't have a timeframe for mac osx, since it needs still a bit of debugging
Can't wait till this little issue is resolved for Mac, seemed to disappear for a bit but its back. Just to confirm I experience it using Modern White Dynamics using the Nebula 3 reverb AU. Cheers for looking into it