Logic Pro 9: New or updated 32-bit Audio Unit Plug-ins sometimes are not available in 64-bit mode
Logic Pro 9.1
32-bit Audio Unit plug-ins that are installed or updated since upgrading to Logic Pro 9.1 do not show up under channel strip inserts' "Audio Units (32-bit)" menu.
Open Logic Pro 9.1 in 32-bit mode to scan the new or updated 32-bit Audio Unit plug-ins. After they have been scanned, they will be available in either 32-bit or 64-bit mode.
See the Logic Pro and MainStage 64-bit FAQ for instructions on how to switch between 32-bit and 64-bit mode.