After installing Zorin OS on the MacBook Air, I was having an issue with it not waking properly from suspend. It looked as though the device was 'awake' but the screen would stay black meaning I had to hold the power button to force shut it down. Searches indicate this is a common issue with various distros, and not just on MacBooks.
Editing Grub, as follows, fixes the issue:
It appears that a combination of trying to save the contents of NVS memory and graphics drivers are preventing the system from waking correctly.