First check and make sure that the plug-ins are actually installed on your Mac.

AU plug-ins are labeled '.component' and are installed in the folder:
Macintosh HD/Library/Audio/Plug-ins/Components.

VST plug-ins are labeled '.vst' and are installed in the folder:
Macintosh HD/Library/Audio/Plug-ins/VST.

If your plug-ins are installed but some/all of them are still missing in KORE, you may need to click the Rescan Plug-ins Now button in KORE's Options (File>Options). (This make take some time depending on how many plug-ins you have installed, so give it a few minutes.)

If this still does not work, then make sure that you have installed the latest updates for your Mac OS and the KORE application, as well as all of the plug-ins you are having trouble with. The version number of KORE itself is displayed on the first page of the About dialog (found by clicking the KORE logo in the upper-left-hand corner of the software interface). After updating, run KORE and rescan the plug-ins again.

Checking plug-in versions on Mac:
You can check the file version of a VST or AU plug-in by selecting the appropriate plug-in file and pressing for ‘Get Info.’ This will open an Info window for the file showing its version number.

Minimum versions of NATIVE INSTRUMENTS plug-ins for KORE compatibility:
The KORE DVD includes plug-in updates for all other NATIVE INSTRUMENTS plug-ins in order to make them fully compatible with KORE. These specific version numbers can be found in the list below.

Important: note that these version numbers are also the minimum required necessary for the plug-ins to work properly in KORE. If one of your plug-ins is not recognized in KORE, it may be because it was not updated properly during the installation process. In this case, you should download the latest updates for each plug-in using the Native Instruments Service Center.

PowerPC Mac:
• Absynth 3.0.3.004
• Akoustik Piano 1.1.2
• B4 2.0.2.004
• Battery 2.1.3.002
• Elektrik Piano 1.1.10.003
• FM8 1.0.1
• Guitar Rig 2.0.1.003
• Intakt 1.0.9.002
• Kompakt 1.0.10.003
• Kontakt 2.0.2.010
• Reaktor 5.1.1.0026.3

Intel Mac:
• Absynth 4.0.1
• Akoustik Piano 1.1.2
• B4 2.0.3• Battery 3.0.1
• FM8 1.0.1
• Guitar Rig 2.2.0
• Kontakt 2.2.0
• Reaktor 5.1.2