From the knowledgebase:
Workaround OSX: Enable the Audio Unit of Halion Symphonic Orchestra
At the moment the Audio Unit component of the new Halion Symphonic Orchestra is not working as expected.
Therefore the AU component cannot be loaded into a host application.
Please download the file “HSO AU.dmg” and run this tool.
After the Installation is completed, the AU Plug-In will work as it is should.
Do this after you have run the regular installer.
Thx for the info. This Tool would not work until I reinstalled HSO and then ran the AU Fix tool and restarted Logic, went to AU manager clicked HSO and it passed. Great. It didn’t appear in the Steinberg Instrument folder in Logic X so I restarted the Mac, hopeful, but it still doesn’t show, so, I still have no access to HSO! Any thoughts?
I don’t know Logic at all, sorry.