HI. The problem may be related to OpenCV library that Orbbec uses for body tracking. I assume all other functionalities do work without any problem.
A suggestion would be to uninstall everything and then first install OpenCV 2.4.8 (This must be the exact version what I have mentioned).
After that a fresh installation of Orbbec Astra SDk 2.0.12 is recommended.
Hope this solves your issue.