I googled "mouse cursor disappears", and it appears to be a fairly common problem and the general consensus is that it has something to do with your display (video) drivers. Here are a couple of sites that exemplify the problem. The one I cited, below, is for a PC, but it shows the idea.
NVIDIA Forums > Mouse Disappearing mouse pointer keeps disappearing - Tech Support Forum
"Firstly this is a known problem. ... Its all to do with how the operating system changes the screen resolution. When you or the system alter the screen resolution (like when you exit a game) the graphic card memory has to be completely reconfigured. This will take a while to complete and the mouse pointer layer of the screen suffers.
Solution 1.
Go to the NVidia web site and download the latest drivers for you card. The fact that your system is less than a year old means nothing. Make sure you have the latest driver.
Solution 2.
Check and make sure that your desktop screen resolution is identical to the screen resolution used in the game. The popular sizes are 640x480, 600x800 or 1024x768. dependent on what size monitor you use and how good your eye sight is.
Will this fix the problem? No it won't. But it should reduce the amount of time it takes for the mouse pointer to reappear."
Most of the responses are from people using Windows, but there are plenty of them from people who use Macs (I googled "mouse cursor disappears macintosh"). I'm not sure if you can update your video drivers or not.
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