Hi, I'm a freelancer so I have experienced this on more than one system (including my own: Mac Pro, Yosemite).
I still use the 4-point perspective tracker for a lot of stuff and find it quite powerful in the right hands.
But it appears that it is virtually unusable in CC2015.
After setting the track points and hitting play, the application will either have a severe crash, or the bounding box (the area that I want to insert the replacement asset) moves itself off screen, away from where I have placed it.
I've just completed a job that required a tonne of motion tracking and I did it using a combo of Mocha, manual tracking and the 4 point perspective tracker. Yet I lost a lot of time having to work around the Tracker crashes.
Anyone else experienced this?
I hope Adobe fixes this ASAP as the tracker is a vital tool in my work.