Quoting this issue from the C9 forums, issue still in 10.5.12:
Enable a multi-out vst instrument track (eg., Geist2) into a project with other audio & group tracks that have automation envelopes, and -
- Enable multiple outs.
- Draw some automation (eg., mute envelopes) on any number of tracks within that instrument.
- Ctrl A (select all) between locators
- Edit -> Range -> Global Copy.
Notice that regular tracks have their automation copied - but that of the multiout vst tracks is not.