What should I do if my sonible plug-ins are not found within Logic Pro X?

If you already have re-started your machine and installed the iLok manager, please follow these steps:

• Clear Audio Unit Cache

1. In Finder, go to Go. Then Go to Folder in the menu bar at the top.
2. Copy-paste the following path then click Go:
   ~/Library/Caches
3. Delete any folder named AudioUnitCache.
4. Delete any file named com.apple.audiounits.cache.
5. Reboot the system.

• Rescan
  
  and/or
• Select the plug-in from the list in the "Compatibility" column of the Plugin Manager
• Click "Reset and Rescan Selection"

Further help can be found here.