I would suggest you to update to the latest version and after you have updated to the upcoming, not yet released, patch please see if you are able to reproduce this again. Also, try and prevent the computer from entering sleep mode or power saving mode as that seem to cause a freeze almost every time for me.
I'll be checking back and see how it goes, please follow this up as it would be much appreciated as we want to have this issue tracked down and solved and knowing if it's something with the game or if it's due to the Mac itself.