When I installed Kstars,there was a checkbox for integration with SkySafari so I checked it.
In the end, I did a clean SkySafari install on another Mac. Then I copied the simulation-curriculum from the containers folder and replaced the one on my MacBook. SkySafari now works correctly.
I suspect that the KAstars install did something to that folder on the MacBook which reinstalls of SkySafari did not correct.