Turning Off the Final Cut Pro Library Sidebar
Some plug-ins, such as Photo Montage, give you a way to select files through a separate window. When invoked from Final Cut Pro, this window lists all Final Cut Pro Libraries found on locally-connected drives.
On some configurations, it is necessary to turn off this functionality to prevent crashes. To do so, follow these instructions:
- Launch FxFactory
- Select the Settings… command under the FxFactory menu to open its Settings window
- Switch to the Advanced section
- Turn off the option titled Show Final Cut Pro libraries when selecting media

The crashes may be linked to a problem with Spotlight, the search engine in macOS that allows FxFactory to locate all Final Cut Pro libraries on connected drives. You may rebuild the Spotlight index by following these intructions:
https://support.apple.com/en-us/102321
Once the index has been rebuilt, you can go back to the FxFactory app and re-enable the same option, so as to easily access your Final Cut Pro libraries.