I did a fresh install of the bundled plugin installer on a new Macbook Pro MacBookPro15,1 with Ableton Live 10 Suite 10.0.5. OS X is at 10.14.1. The AU versions of the plugins are installed in the right place but they do not show up in Ableton Live. Please advise.

Ok, seems a restart is required. It is showing now.

Yes, sorry. It is a well-known problem that the last two major MacOS updates may require a restart to discover newly installed Audio Units. Specifically it seems to be a problem with Audio Units that are based on the original "component manager dispatch mechanism". Our future releases will use a more modern mechanism and should not suffer from this problem.