Use the play button in the mask path to track the motion across your clip.
If you need to create an effect where a mask becomes the new frame (e.g., "Iron Man HUD zoom" or "Map zoom"), do this for free: Mask To Transform Plugin For Adobe Premiere Pro Free
Here is why:
The plugin will instantly generate keyframes matching the original object's movement. Common Troubleshooting Tips Use the play button in the mask path