Strange issue when using Halion Sonic 3 as a plugin.

When I use Halion Sonic 3 in standalone mode and load a patch, a good example is “Dark Secret” All the elements in that patch are perfectly balanced, but if I load Halion Sonic as a plugin, (Audio Unit in Logic Pro X), the elements that make up the patch sound completely different.

“Dark Secret” has this lovely sound in the higher frequencies that is lost when I load Halion Sonic 3 as a plugin.

I have checked the settings for the patch and they are identical in each instance, so I can’t pinpoint what has changed to fix the sound.

Any ideas?