Running alpha 30.1-8 on OS X 10.11.6, El Capitan. I can start the game through Steam just fine, and get to the main menu. Then, when I either start a new airport or try to load an existing airport, I get to the loading screen (see screenshot), which then hangs. Sometimes it just outright freezes; other times, the progress bar keeps flipping back and forth between a couple different items (I believe usually businesses and something else).
I haven’t been able to find any smoking gun log files to diagnose. I’ve tried starting the game on the laptop display and the external display, changing the screen resolutions, as well as starting the game with the external display disconnected.