Have you tried to Reset Printing system on your Mac:

https://support.apple.com/kb/PH25565?viewlocale=en_US&locale=en_US

You can also try to delete all custom paper sizes on your Mac and than recreate them as needed.

After resetting Printing System (deleting all printers) - try to edit page setup in some of your drawings.

If AutoCAD will not crash - add printer(s) again one by one and check Page Setup editing in AutoCAD.

Maxim