Cannot set Keyframes to Linear when the object is being masked

I made the effect in Motion. It's a mask that goes over the Source. 
Once I have it in Final Cut Pro , however, when I move the source to animate it under the mask, I have no way of changing the keyframes to Linear. 

When I open the video animation and then click on the transform box, the keyframes aren't showing. 

I've tried setting the animation keyframes in the Motion timeline to linear but (possibly because there is no animation in the Motion project and it wouldn't relate to the motion I am doing anyway) it doesn't have any effect. 

can anyone help? 

I suppose I could export as xml and then fiddle there but, my god!

It's frustrating that I can't default final cut pro to linear. Or change them any other way than zooming out the timeline to 12.5% and trying to right click on the nodes. 

Would you be willing to post the Motion project file, with an explanation of the problem you were trying to solve with it?