"Quits unexpectedly" after training without saving

Zwift wasn’t stalling on my Mac Air - so I did a apple software upgrade - Zwift now opens with the black screen “running processes” page and then opens up in the Zwift. I start training, finish, the click the Save & Exit - then it “unexpectantly quits” Any ideas please? It didn’t save my ramp test today!
Perhaps I should uninstall Zwift, and then reinstall? Hopefully this won’t delete my history.

Zwift wasn’t “stalling” or “installing”?

Which MacBook Air? What version OS X are you running?

Uninstall and reinstall can’t hurt. Your ride history among other things are stored on Zwift servers.

Thank you - I’ll try reinstalling.