Track Matt not working

[Warren Krige]

I want my cupcake shot to 'grow' in scale while remaining within a bounding box. Problem is the track matt seems to grow with the clip (See the video clip attached). I have nested the cupcake shot and applied the scale effect within the nest. I did this because I see in other posts the Track Matt does not work well with other motion in Premiere Pro. In the screenshot, you can see I have set the Matt as V4. The video matt is a square PNG. 

What am I doing wrong?

[Ann Bens]

Please show screenshots entire Effect controls of nest (now is just showing half) and square.

You need to apply the scale to the clip inside the nest.