Hello Lyn, are you aware of the macOS requirements of version 4.3.20 ?
If not, the supported versions are
minimum OS X 10.10.5 (Yosemite) until maximum macOS Mojave (10.14)
When using the software with a newer, unsupported operating system you do so at your own risk.
That being said, you can detach the inspector from the main window over the settings as explained in this thread:
https://forum.projectwizards.net/d/141-inspector-color-scheme-issues
That solves the issue with the inspector, but we have no way knowing which other issues you might encounter using such an old software version on a current macOS.
Best regards