AO Ex Causing SU to Hang

I am using AO Ex (2.01), SU2018 on a Mac running 10.13.5. After I render a scene, save it, and close the AO window, SU will become unresponsive - but it doesn’t show as hanging, either. It happens every time I render. If I open Activity Monitor and kill the Window Server process I can continue using SU, but this is not a good solution. It seems like AO is still running in the background, and expecting some input, or not giving control back to SU. I can reproduce this every time I render.