Cubase 9’s new Plugin Manager called Sentinel blacklists plugins if you’re using an old version of OS X (before macOS Sierra), if some conditions are given:
The Deployment Target of the plug-in is < 10.8 and “Implicitly Link Objective-C runtime Library” is set in XCode’s Project settings.
When saved with Projucer, XCode’s “Implicitly Link Objective-C runtime Library/Support” has the value “yes”. So to my understanding, all plugins that are saved with Projucer and Deployment Target < 10.8 will be blacklisted in Cubase 9’s Plugin Manager.
With a fresh built of Projucer made with the develop tip, I confirm that if I just create a new plugin project, export and open in xcode 8.0, I have CLANG_LINK_OBJC_RUNTIME to YES, as Jakob.
Actually you’ve been right - “Implicitly Link Objective-C runtime Library” is set to off when saved with Projucer. I was also misled by looking at XCode’s project settings, instead of at the target settings.