hm, might just be a compatibility issue with the new Mac. Maybe you can try to look for the log file. It should be somewhere here:
~/Library/Logs/Company Name/Product Name/Player.log
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I think with Ashtorak and StarbaseSim as Company and Product Name.
However, I don't do any Unity development any more, so I don't know, if I can help you right now. When the Unreal version is out on Steam, I will look into doing a Mac build of this. Maybe wait until then.