In March of 2012, Apple required that all apps submitted to the Mac App Store be sandbox-safe. This means that the application is required to specify which external resources it needs in order to work properly. This is for security purposes and helps to prevent malicious code from accessing the rest of your system. Most Audio Unit developers have patched their plug-ins for sandboxed apps. Those that haven't have the unfortunate side-effect of authorization issues. In some cases simply re-entering your plug-in's serial number just once will keep it licensed and activated from then on.
Here's a list of known plug-in manufacturers that have NOT sandboxed their Audio Units plug-ins:
- DMG Audio
If you encounter others, don't hesitate to let us know. While we have contacted these developers, we suggest that you do so as well. This, no doubt, requires some effort from us and third-party developers, but results in an overall better experience for you.