Mine is a guest related issue where now I am losing 50k a year, something they have broken since the last update. With corrupt save go into my zoos and delete the most recent file if you have backups and load the back up, sometimes this works and you can play it again.
I'm not gonna play again until they fix the save issue, which is a pain because I LITERALLY just bought the Arctic DLC
Released an update that turns off the guest refunds, may zoo is now profitable now. Not changed a thing, no guest randomly leaving and making 50 to 100k profit a year now. Hopefully they fix the issues before they turn guest refunds back on.