Problem
After upgrading to Logic Pro X 10.2.2 my install seemed to be missing content (in my case mainly Plugin Settings, although I’ve read reports from people missing anything from EXS instruments to Alchemy patches or complete Drummers). All additional content had been installed as witnessed by the Sound Library Manager. Deleting the Logic application file and re-downloading from the App Store (in order to re-establish a connection with the Apple homeland in the hopes of triggering a “install missing content” menu-option) does not help.
Hours of web-surfing finally brought a not-completely-obvious solution, which I’d though I’d share with the world since during my search I ran into various pages describing similar problems without a solution.