Just tried to access the game data.json file and when I go to the:
~/Library/Application Support/unity.Apoapsis Studios.Airport CEO/Saves
directory there is only 2 saves in there from Feb 2018 - has the directory been updated in new releases since?
I’m using latest edge update on Mac oS High Sierra
No, that is the folder we use for saves. If you go into the game, do you see more saves?
I’ve just found them in /Users/Macbook/Library/Application Support/Apoapsis Studios/Airport CEO/Saves
Any suggestions why mine would be in a different location?
Strange, not really. I’m not a Mac user, maybe the latest version did something to the folder structure. Will note down that path for other users if we run into a similar issue. 
Mine is stil in this location, so not sure why yours has moved. HS as well.
Just checked and all saves still in the same original location
A mac works in mysterious ways… if you purge the folders and do a reinstall (save any save files first) does the same behavior still apply?
Steam has changed all saves for all games. So the “go to game files” in steam, you have to go back a few folders and then find the AirportCeo.ApoasisStudio.game or something like that.
When did that happen?
A while ago.