Selecting an item for an installed library in the Libraries Reference menu does nothing

Expected Behavior

The reference for the installed library should open

Current Behavior

Nothing happens

Steps to Reproduce

1. Install a library from the Contribution Manager (eg Syphon)
2. Select that library in Help > Libraries Reference > Syphon
3. Nothing happens

Your Environment

• Processing version: 3.5.3
• Operating System and OS version: macOS 10.14.4