I first noticed it on the Vegas 22 release, but now the latest patch also has completely broken Motion Tracking for me.
After tracking something, just slightly moving the event on the timeline breaks the tracking. The only way you will notice it is if you close the motion tracking window and re-open it, because the program keeps showing an intact tracking while it's actually fragmented. It keeps working flawlessly on V21
Here's an image of the fragmented tracking on V22