Product: Platinum, Gold
Version: 4.8.1

Description:
If multiprocessor support in Logic is enabled you can't hear ReWire channels. As soon as you reboot Logic after deactivating multiprocessor support it works.

Explanation:
Please read the following excerpt from the 4.8.1 update-info:

- Currently ReWire by Propellerheads does not support Apple's multiprocessor technology. Activating 'Multi Processor Support' in Audio > Audio Hardware&Drivers could cause system overloads and playback interruptions in previous versions of Logic Audio (Platinum / Gold). To prevent this, ReWire is no longer available when 'Multi Processor Support' is active in Logic Audio.

Solution:
The problem has been solved with Logic 5.2.