I've been having problems with installing Xcode 9 (and 8) extensions. Take a typical Xcode extension like xcsort. Run the application. Open the Extensions system preference pane. Up until recently, there would be the xcsort Xcode extension right there with a checkbox to enable it. Enable it, run Xcode, and voila!, there it is in the Editor menu. Now, you do the same process, and nothing shows up in the Extensions preference pane, and, consequently, not in Xcode. Use to work fine, not it's not. Pretty sure it was working for High Sierra and Xcode 9.0 general release. All of a sudden it's gone.
Any clues about how extensions are stored, how the preference pane is notified, etc.. As far as I can tell, the application runs without problem, the extension is just not available.
Any help would be appreciated.
Jon
