Masking and Motion tile issues

Motion Tile works on layer size. It does not take into account the transparent pixels on the outside of your mask.

The workaround is to pre-compose the layer and then resize the pre-comp to the dimensions you need. Then you can add motion tile to the nested comp (your pre-comp) and it will work as long as you don't collapse transformations.

Ye honestly can't know. You have to provisde a screenshot of the whole thing and settings and/ or explain in much more detail how your comp is set up, what layer you are applying the effect to and all that.

Mylenium