Good news - I have found and isolated the issue, which turns out to be a single line of CMake script. I am running more tests and will have a new update, hopefully before Friday. Sorry for the delay (I am a one-person team with a day-job) but the good news is that it was very minor and does not involve any changes in the ASPiK core code. 

Stay tuned - 

Will

OK the v1.6.4 update has been released. The simplest thing is to just start a new project. If you've done work with adding controls, etc... then you can copy your plugincore.h and plugincore.cpp files to the new project and that should restore things (unless you added other files on your own).

There were two issues with AU and the Cocoa GUI - one was a simple CMake script line of code and the other involved the naming of the AU bundle when building for Universal projects. In this case, you will see that the letters "_AU" have been appended to the target name to differentiate the three targets (plus the Cocoa GUI target) from one another. That addition of "_AU" was a separate, but also problematic issue, and that has also been corrected. 

I also corrected a memory-creep issue with the custom view demo projects. There was a very minor memory leak (32 bytes) in the vst3plugin.cpp file which was fixed with a simple delete call. New projects will have this updated file, and you can copy it to your old versions if you want to. 

Thanks for reporting this - it had different behavior in different hosts. But, the GUI Designer is now available for you as a result. 

ONE THING: go to your ~/Library/Audio/Plug-Ins/Components folder and find and delete the AU plugins from v1.6.3 (the ones you've had problems with). You may note that some are actually zero-bytes in length. In any event, just get rid of those manually before rebuilding new AUs. 

Will