When using Pixsort my AE quits unexpectedly almost immediately every time. Any fix on this would be great. It is unusable for me right now. I'm using a maxed out Mac 10.11.6 so there should be no issues with my hardware.
What version of After Effects? Do you have any crash reports that you may provide to give further insight on the issue?
In your /Library/Logs/CrashReporter directory there should be a crash log for After Effects. Can you possibly upload this file somewhere so I may see what exactly is going on?