I have been encountering a really annoying bug while editing on my 2015 Macbook Pro 13". I have the early-2015 model with i7 processor and 16gb of RAM and 512gb of storage.
Every time I use track motion to put a text over a video clip and hit play, the whole app turns unresponsive. It just continues on playing the whole sequence on repeat, and there is nothing I can do. I can't click on anything as the spinning beach ball icon pops up. This happens almost every time I use After Effects, as I mainly use it for tracking motion. This is really frustrating as I always have to force quit and start over, and even better, I see the finished work playing on repeat but I can't save it. It is like After Effects wants to rub salt into my wounds.
What, exact, version number of AE are you using? Is it 14.2.1.x?
Which tracking feature are you using? There are several.
What format and codec is the footage you are using?
What number is your MacOS?
Are you still facing this problem? If not, let us know how you solved it. If so, please let us know so we can assist you further.